# Gel coat blisters



## superiorvoyager (Jan 3, 2009)

Planning my projects for the spring with repairing the deck around the mast step first but also am developing a problem with Gel Coat Blisters. I believe the hull (under water) may already have been repaired but over the last few years I have been developing little blisters the size of a pencil eraser on the Hull above the water line. 4 years ago there were only a few but now they are probably covering about 40% of the hull (above the waterline). Some are starting to crack but most are still just little bumps, almost looks like the hull has a rash. Not noticable from a distance cause they are so small but up close looks bad. I've dug out a number and they are dry inside so not concerned about that but they are spreading, probably twice as many as there were last year. As I said there are lots, in the areas effected, 100-150 in a 1"circle. SO how do I repair this. Most advice says to dig or grind out the blisters but with the amount I now have that would take forever and I would still have the problem of new blisters. My thought is to sand the gel coat down on the whole hull, seal it and then paint with 2 part paint. Any better ideas?


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## sailingdog (Mar 19, 2006)

It would help if you said what kind of boat this is on, and whether the boat was painted or not. If the blisters are dry inside, then it is likely that they are not OSMOTIC blisters, but most likely due to some contamination of the gelcoat during the layup process. 

Unfortunately, fixing them is going to require sanding them open, filling and re-fairing the area with thickened epoxy and re-gelcoating or painting the area.


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## superiorvoyager (Jan 3, 2009)

It is a 32' voyager Ketch. The hul is not painted just old gel coat. I understand that the usual practice is to sand them open, fill and re-fair the area with thickened epoxy and paint the area but with 40% of the hull effected I would see the need to repaint the entire hull. As well what will stop the rest of the gelcoat from developing blisters after it has been painted. Between last year and this year the affected area has at least doubled. Would it make more sence to just remove the entire gelcoat seal it and paint it. And if so what would be the best way to remove the gelcoat. I also suspect that there is a problem with the gelcoat and would think that just filling the effected area leaves the possiblity of the rest developing the same problem.


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## Stillraining (Jan 11, 2008)

Hire a company to "Peal" the hull...you can buy the tool yourself for 800.00 or so but it is a little tricky to not go to deep.

I have heard ( Not verified ) that a 30' hull around here costs about a grand to have peeled...it only takes a day for some one who know what there doing I guess.

I have only seen the hulls after the fact I haven't had the pleasure of seeing it done yet...so take all this with a grain of salt.

But what I have seen it does a very nice job and it is amazing to see how much of the glass never got saturated on some of these boats.


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## Stillraining (Jan 11, 2008)

I Should clarify that was for below water line so a whole hull would be considerably more.


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## superiorvoyager (Jan 3, 2009)

The problem is that is far as I know there is no one around here who does this kind of work. In Thunder Bay there is a fellow who does blister Jobs below the water line but he grinds the hul down doesn't peel. That would still mean Transporting the boat 120km. Otherwise I wouild probably have to haul the boat 1000-2000 km to get the job done. As well, Below the water line there is no indication of blistering and I suspect it might have allready been repaired if there had been a problem. It there a do it yourself way of successfully stripping the Gell coat?


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## tommays (Sep 9, 2008)

Being able to dry out a hull enough OUTDORS so they wont come back is the subject of a lot of heated debate


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## mitiempo (Sep 19, 2008)

I don't think the peeling machine is that big - they could travel to the boat wherever it is.
Brian


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## osirissail (Oct 27, 2009)

You really do not want to peel or sand off the gelcoat above the waterline. You will end up with a supremely ugly boat. The normal "fix" for gelcoat blisters above the waterline is to individually using a very small tool route out and dry the existing gel coat blisters use heat lamps to assist the drying, but keep the temperature of the hull low enough that you can place you hand on it without burning your hand. The use thickened epoxy filler to individually fill each blister and when cured sand it smooth - very carefully. Then an epoxy topside paint to paint the boat. Do not use a polyeurthane paint as it is not compatible with epoxy and that type paint will also develop blisters is repeatedly immersed in water. The epoxy paint acts like a barrier coat to help prevent new gel coat blisters from forming.


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## Stillraining (Jan 11, 2008)

Agreed...Below water line peal..but above ....boy absolute last resort.

How bad is it really? any pictures?

I mean if your boat has Leprosy and parts of it are falling off then yes pealing would be in order..but if it is cosmetic only then weigh the effort and cost and probable poor looking out come to its current value and your current ability to enjoy the boat in its current condition to what you will gain.

OK so it has a bad case of acne...it still has a useful life...no?

I would not peal myself but sand down the affected ares to the roving and repair those using the unaffected ares to fair into. It may take several years to get them all as new areas developed but that is in my mind a doable way of getting or maintaining a nice faired hull.


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## superiorvoyager (Jan 3, 2009)

interesting resonses. The blisters are totaly dry so why do I have to dry them out? Getting someone to travel 1500 km or more to do a peeling job would probably be very expensive so that would be out. Digging out and refilling each blister sounds like it would take months. I had been hoping to paint the hull just for looks this year as the gelcoat looks so bad but it probably makes sence to just leave the boat with a bad case of acne and sail it as it is.


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## osirissail (Oct 27, 2009)

- - Actually, unless the boat is laid up with vinylester resin the underlying polyester resin is not dry. Polyester resin does absorb considerable water. Grinding out the small blister with a dremel or similar tool takes at most a day or two. Let the boat sit out of the water for a week or two in the sun and the hull will dry sufficiently to allow the epoxy filler putty to adhere. Patching the little "pocks takes at most a day. You use a wide trowel and wipe (like plastering a wall) epoxy filler across dozens of little "pocks" with each stroke. Another week to cure the epoxy and then light sanding to fair the hull before painting. Just painting over the gelcoat blisters won't hide the hundreds of little bubbles from being seen. Since it is all a "cosmetic" fix - you can decide how "fancy" and "pretty" you want the boat topsides to appear to your eye. All subjective - beauty is in the eyes of the beholder. . .


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## mitiempo (Sep 19, 2008)

The blisters cannot be totally dry as without the moisture or gas the blister wouldn't have formed - the pressure of the moisture or gas is what pushed the gelcoat out to fom the blisters. You won't necessarily see water inside the blister but moist gas does exist inside them. I wouldn't peel the topsides but just painting over the blisters probably isn't a good idea in my opinion. You said that there are 100 to 150 blisters in a 1" circle - do you mean 1 foot circle? If it's above the waterline all the time and water isn't in constant contact with the hull there is some kind of chemical reaction taking place to cause them. Covering them with paint of whatever type will not stop this from continuing to happen I don't think.
Brian


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## superiorvoyager (Jan 3, 2009)

Just laid a quarter over one of the bad blister spots and counted 19 of these blisters. They are very small. When you consider that about 40% of the boat has these, (above the water line only) you can imagine how big the problem is. Using a dremil is more work than I wan tto undertake. Maybe using a sander to pen them all up an then filling would be the way to go. Maybe just wait a few more years.


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## osirissail (Oct 27, 2009)

Gelcoat blisters vary in size from pinpoint - as yours seem to be - to 1/4" or larger. They are characterized as blisters that do not penetrate deeper than the gelcoat layer of the boat. (They do not extend down into the laminate below),
- - With the pinpoint ones like yours - your idea of just sanding off the tops is what is actually done. Use a fairly large board/plank type - I like a 4 x 6 piece of plastic board (e.g. Kingboard or Starboard) and attach/wrap a fine grade sanding paper to it. Then gently track back and forth over the little buggers to reduce them to the existing level of the rest of the good gelcoat. The idea is to not sand down into the good existing gelcoat or to make "dished" depressions into the gelcoat - just get rid of the tops. 
- - Depending upon how "fine" you want the finished job appear - with a first coat of primer you need to break the little bubbles that will form over the remains of the little pits. Some call it "spotting". I use a special 1" double ended spatula tool. It has a pointed shape on one end and a flat surface/end on the other. Something like a tool an oil painter would used to move his oil/acrylic paints around a canvas.
- - Once you have succeeded in getting a layer or two of paint/primer over them with no bubbles forming - then you are ready to apply the topsides paint.
- - The "board sanding" goes very fast, the first coat of paint/primer and smoothing the little bubbles away takes a little longer. Finally the topcoats of paint is variable based on the actual paint system you chose to use and whether your spray it or brush it on.


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## Maine Sail (Jan 6, 2003)

superiorvoyager said:


> Planning my projects for the spring with repairing the deck around the mast step first but also am developing a problem with Gel Coat Blisters. I believe the hull (under water) may already have been repaired but over the last few years I have been developing little blisters the size of a pencil eraser on the Hull above the water line. 4 years ago there were only a few but now they are probably covering about 40% of the hull (above the waterline). Some are starting to crack but most are still just little bumps, almost looks like the hull has a rash. Not noticable from a distance cause they are so small but up close looks bad. I've dug out a number and they are dry inside so not concerned about that but they are spreading, probably twice as many as there were last year. As I said there are lots, in the areas effected, 100-150 in a 1"circle. SO how do I repair this. Most advice says to dig or grind out the blisters but with the amount I now have that would take forever and I would still have the problem of new blisters. My thought is to sand the gel coat down on the whole hull, seal it and then paint with 2 part paint. Any better ideas?


These can often be caused by an inept and unskilled shrink wrapper. The heat from the shrink gun heats any moisture trapped in the laminate and the gas trying to escape causes the blisters..

Not really much you can do short of either sanding it all flush and re-fairing the entire top sides or peeling it. Trying to tackle this type of wide spread blister, 19 blisters in the size of a quarter, with a Dremel, is a life sentence of hard labor..


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## Stillraining (Jan 11, 2008)

Going back and re-reading my own posts I confused even myself.. 

So just to clarify...I'm all for pealing below water line..never above it unless it is absolutely needed.

I agree with board sanding in your case as it does not sound like osmosis blistering to me..something else is going on there...it is just to weird...too small of blistering for osmosis blisters.

I'm getting old and lazy ..I have one of these..they can be had for less then 50 bucks...rent a contractor grade wheelbarrow air compressor..you will be done in a couple of hours..

But as I said before... if more are developing yearly..why bother right now..just sail it...unless you have an abundance of energy and don't mind having to see your work ruined I would wait another couple years and see what transpires.

If you are worried about water penetrating through them and causing more damage by turning them into osmosis blisters then that is a different story and I would deal with them now and just take it on the chin if more developed later down the road....maybe a couple coats of wax would take care of that issue...or even that poly shield junk..after all you will be eventually sanding everything off anyway....might be a stop gap measure for the time being.

Question...Was your boat ever next to another one in a yard that was getting chemically striped or spray painted with out being tented or anything like that?


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## superiorvoyager (Jan 3, 2009)

Stillraining said:


> Going back and re-reading my own posts I confused even myself..
> 
> Question...Was your boat ever next to another one in a yard that was getting chemically striped or spray painted with out being tented or anything like that?


I have only had the boat for 4 years and in that time it was never near a nother boat that had anywork done on it. I did use the Poli Glow system on it when I first got it though. I tried to take a picture but it doesn't show up well. Sounds like my choices are to sand and paint (i'd still have to fill the various chips and scratches) or leave it. If I sand and paint what should I do about the blisters with cracks in them?


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## superiorvoyager (Jan 3, 2009)

Another question. It was recomended sanding them down with a flat board and sandpaper (I call that a shooting board) but why not use an orbital sander?


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## Maine Sail (Jan 6, 2003)

superiorvoyager said:


> Another question. It was recomended sanding them down with a flat board and sandpaper (I call that a shooting board) but why not use an orbital sander?


Because you most likely wont wind up with a fair hull and it will look like a golf ball when done.


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## sailingdog (Mar 19, 2006)

Maine Sail said:


> Because you most likely wont wind up with a fair hull and it will look like a golf ball when done.


ROFL...nice description... pretty accurate too...


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## Stillraining (Jan 11, 2008)

superiorvoyager said:


> I have only had the boat for 4 years and in that time it was never near a nother boat that had anywork done on it. * I did use the Poli Glow system on it when I first got it though. * I tried to take a picture but it doesn't show up well. Sounds like my choices are to sand and paint (i'd still have to fill the various chips and scratches) or leave it. If I sand and paint what should I do about the blisters with cracks in them?


Maybe you found your culprit...who knows.... could have been a bad batch or bad match to your hull for some reason...something strange is going on for some reason .

Are you sure it is gel coat... and it hasn't been painted already?.....Just a thought.

Treat the actual osmosis blisters individually.


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## osirissail (Oct 27, 2009)

superiorvoyager said:


> Another question. It was recomended sanding them down with a flat board and sandpaper (I call that a shooting board) but why not use an orbital sander?


As Maine Sail stated you do not use any form of rotating sander including your hand. You will get "dishes" - circular hollows that when anybody looks down the the length of your hull will be very obvious and quite unsightly. Only the long flat surface of a board or board sander can span enough distance to prevent getting lots of dishes/hollows. When apply a primer over the sanded down "pits" and use a tool to smooth it - remove bubbles - minute cracks will disappear. How much time you spend at this will determine the "beauty" of the paint job.


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## RichH (Jul 10, 2000)

Cosmetic gelcoat blisters at the waterline are quite common with some boat manufacturers. The key word here is 'cosmetic' and are probably from 'sloppy' gelcoat spraying of the original layup. Most above the waterline blisters are probably caused by contamination of 'mold-release' compounds that somehow migrate (splashed??) when a contrasting gel color is used/sprayed for the bootstripe.

Above the waterline gelcoat blister remediation is EASY for anyone who is fastidious and who has a modicum of 'artistry'. All you need is computer color-matched gelcoat, a dremel tool, etc. and a bit of 'sweat equity' to do a proper job; although, Id recommend 'practicing' on an old dinghy, etc. before attempting a gelcoat topsides repair. There are many 'forum discussions' on the net that you can obtain info on how to do fast and easy gel repair. Do websearch for: "gelcoat + repair", etc.

The color-matching is THE important aspect of gelcoat repair. Dont depend on your eyeballs, but simply cut a small shallow 'plug' from topside and send it one of those companies who offer 'optical computer matched' gelcoat. They will also be able to supply the proper 'overcoats' that are sprayed on to help level the applied gel so you have less work in 'flattening' the repair work. Be sure to first CLEAN the hull with strong caustic soap, followed by a wash/soak of oxalic acid to remove any staining, etc. before using new gel or before sending the 'plug' to the color-computer. Small repairs can be done with a simple plastic trowel, larger areas can be easily 'sprayed' with small disposable and self contained (pressure and container) ***PREVAL*** spray guns (Preval Paint Spray Gun Kit), or inexpensive 'gel spray guns'. Depending on the thickness of the original gel, You may even be able to simply gouge out the blisters of non-adhering gel, slightly 'sand' the base of the 'crater' and fill with color-matched gel . using only a plastic trowel .... then sand down the area with successive wet and dry paper (400--->800--->1300--->2000 Grit wet and dry sand paper and then 'buff out' the area with successive finer and finer compounds course---->3M finese-It---->3M Perfect-It, etc. The goal is to get the gel back to FLAT before buffing. etc. etc. etc. etc.

Suggest: Fiberglass Repair: Vol. 1 - How To Repair Gelcoat ..... then beg, borrow or steal on old dilapidated dinghy and 'practice' your gel repair on that first. Most times if using computer color-matched gel for 'craters, gouges, and 'blisters' - you wont even need to spray the overcoat, etc.

You DONT need to peel the topsides, you DONT need to take ALL the gel off, .... and you really dont need to be distracted by those who havent actually done this. 
Gelcoat repair and restoration is not some 'inviolate or forbidden process' relegated only to vestal virgins. Its easy and can be quite satisfying - if you are fastidious. Re-gelcoating is vastly superior to any 'paint' process. There is LOTS of good info on the web concerning gelcoating, its repair and restoration.

Painting a hulls topsides, ultimately, is only 'temporary', can be extremely expensive ..... and after a few years will look like $H!T when the topside paint inevitably loses its adhesion due to its (as stated in all the tech manuals) 'incompatibility with moisture or wet environments' - as there is NO topside paint made on the planet that will withstand the 'wetness' of a waterline constantly 'dipping' into the water.

Ignore the boo-birds, the sky hasnt fallen ... and best of all you need not employ drastic and extreme (and totally inappropriate) methods to get your hull back to the 'luster and showroom new shine' that makes one proud.

hope this helps.


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## Maine Sail (Jan 6, 2003)

RichH said:


> You DONT need to peel the topsides, you DONT need to take ALL the gel off, .... and you really dont need to be distracted by those who havent actually done this.


Rich,

I agree with everything about gelcoat repairs however this guy has a serious problem. _*"19 pin holes in the size of a quarter and 40% of the boat is covered"*_. It's not like he has a few along the waterline as we've all seen.

I have seen this before, often caused to show up after an over zealous yard monkey hit the hull in one to many spots with the heat shrink gun, and doing spot by spot gel repairs on this wide spread of a problem would be extremely time consuming. Could it be done? Sure, but how long do you want to spend??



RichH said:


> Painting a hulls topsides, ultimately, is only 'temporary', can be extremely expensive ..... and after a few years will look like **** when the topside paint inevitably loses its adhesion due to its (as stated in all the tech manuals) 'incompatibility with moisture or wet environments' - as there is NO topside paint made on the planet that will withstand the 'wetness' of a waterline constantly 'dipping' into the water.


A little bit of an exaggeration? You've seen Tim R.'s red Ericson with the fire engine red Imron? That Imron is 20 years old, no blisters or bubbles and it gets used hard and put away wet. The paint still looks nearly new even twenty years later. My neighbor Tom's boat has 18 year old Alwgrip, again no bubbles, no blistering. My friend Paul's Alberg has Awlgrip exceeding 24 years and while showing slight fading the boat still looks good and has no blisters or bubbles. To say a "few years" is slightly unrealistic. No?

While there is no doubt to me that I prefer gelcoat there comes a time when you have to decide whether it is actually salvageable. 19 pin holes in the size of a quarter and the boat is 40% covered in them seems to me like it's time for a re-finish? But what do I know I've never done any gelcoat repairs.. Except of course when I built boats and worked in boat yards ...



RichH said:


> Ignore the boo-birds, the sky hasnt fallen ... and best of all you need not to employ drastic and extremely methods to get you hull back to the 'luster and showroom new shine' that makes one proud.
> 
> hope this helps.


I don't think there were many boo-birds, but some of us who have actually done gelcoat repairs looking at a stated 40% of the boat covered in pin holes (19 to the size of a quarter) trying to guide this guy into not wasting his season away gouging, Dremeling & filling & re-gelcoating thousands & thousands of holes. Some of us just don't consider re-finishing a boat covered 40% in massively thick blisters "drastic" I guess...

I love gelcoat, and am one of its biggest proponents, but if that was my boat she would be re-finished..


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## superiorvoyager (Jan 3, 2009)

Even if I repair all the holes with computer matched Gel coat it would still look like crap as there have been numerous gel coat repairs on this hull over the years all of which are a little different shade. As well there have been a couple of repairs that someone painted over instead of using gel coat as well as a couple of deep gouges and then one spot where the boat must have rubbed against something and wore all the gell coat off over about a 6" area. So it needs refinishing eventually anyway. What would you recommend for paint? I've had people recommend Interlux perfection as well as awlgrip.


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## mitiempo (Sep 19, 2008)

I think Awlgrip is top choice, closely followed by Interlux Perfection. If you're going to do all the proper prep you should use the best paint.
Brian


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## sailingdog (Mar 19, 2006)

Imron and AwlCraft are also excellent choices and unlike AwlGrip, repairable if they get scratched IIRC....


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## RichH (Jul 10, 2000)

Maine Sail said:


> Rich,
> 
> A little bit of an exaggeration? You've seen Tim R.'s red Ericson with the fire engine red Imron? That Imron is 20 years old, no blisters or bubbles and it gets used hard and put away wet. The paint still looks nearly new even twenty years later. My neighbor Tom's boat has 18 year old Alwgrip, again no bubbles, no blistering. My friend Paul's Alberg has Awlgrip exceeding 24 years and while showing slight fading the boat still looks good and has no blisters or bubbles. To say a "few years" is slightly unrealistic. No?
> 
> ...


Simply take a good look at any 'painted' boat that has been over on her sides heeling for a few days while on passage, ditto any painted boat that was shrinkwrapped and had any of the 'wrap' touching the painted surface, ditto any boat with painted topsides thats slipped or moored in an area where the topsides constantly 'dip' into the water. In all those cases you will find that the paint WILL lose adhesion and either 'crater' or form blisters.

My first exposure to this was on a boat painted/sprayed with Interthane .... lost most of its paint 2-3 ft. above the waterline while 'beating' to Bermuda; Second - 'craterd' a hull painted with Interlux 900 series when condensation formed under shrink wrap .... boy was I pissed as 900 series is/was mega-expensive and a ***** to spray; Third - lost/blistered the Awlgrip on a boat that was slipped in a 'rolly' location which caused the boat to constantly 'dip' beyond its waterline ....... and when you look in the 'tech manuals' for all these 'paints' they all will have the documented listing of to be use only in applications that essentially 'remain above the water'. I was one of the first to report to Interlux the problems of shrinkwrapping which lead to subsequent manuals/instructions that such painted boats NOT be shrinkwrapped .... I got free replacement paint but had the pain of completely redoing and entire hull topsides (spray and buff job).

Have you ever tried to repair the paint (gouges, etc.) on a 'painted' hull? .... nah, gimme gelcoat easier to color-match, easier to level and flatten .... and most of all its the easiest to repair and easily buff-out. To do a proper 'paint job' requires humongous prep - and, I think, much more total work than to do a simple gel repair.


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## superiorvoyager (Jan 3, 2009)

mitiempo said:


> If you're going to do all the proper prep you should use the best paint.
> Brian


That's why I asked. I want to do the best Job possible with out too much time or money. I assume spraying is preferred (I may be able to get someone to spray it for me) but I like the fact that Perfection can be rolled on and a boat I saw with the finish rolled on last year looked great.


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## Stillraining (Jan 11, 2008)

RichH said:


> Simply take a good look at any 'painted' boat that has been over on her sides heeling for a few days while on passage, ditto any painted boat that was shrinkwrapped and had any of the 'wrap' touching the painted surface, ditto any boat with painted topsides thats slipped or moored in an area where the topsides constantly 'dip' into the water. In all those cases you will find that the paint WILL lose adhesion and either 'crater' or form blisters.
> 
> My first exposure to this was on a boat painted/sprayed with Interthane .... lost most of its paint 2-3 ft. above the waterline while 'beating' to Bermuda; Second - 'craterd' a hull painted with Interlux 900 series when condensation formed under shrink wrap .... boy was I pissed as 900 series is/was mega-expensive and a ***** to spray; Third - lost/blistered the Awlgrip on a boat that was slipped in a 'rolly' location which caused the boat to constantly 'dip' beyond its waterline ....... and when you look in the 'tech manuals' for all these 'paints' they all will have the documented listing of to be use only in applications that essentially 'remain above the water'. I was one of the first to report to Interlux the problems of shrinkwrapping which lead to subsequent manuals/instructions that such painted boats NOT be shrinkwrapped .... I got free replacement paint but had the pain of completely redoing and entire hull topsides (spray and buff job).
> 
> Have you ever tried to repair the paint (gouges, etc.) on a 'painted' hull? .... nah, gimme gelcoat easier to color-match, easier to level and flatten .... and most of all its the easiest to repair and easily buff-out. To do a proper 'paint job' requires humongous prep - and, I think, much more total work than to do a simple gel repair.


OK so are you saying Jeff to apply more gel coat rather then painting?


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## osirissail (Oct 27, 2009)

- - Here is a better solution to the gouges, blisters, discoloration, etc. Sand down to fair then fill all the stuff possible and apply a hi-build primer to the topsides. The find an artistic friend and supply lots of beer or rum and different color topside paints and do something like the below:


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## superiorvoyager (Jan 3, 2009)

osirissail said:


> - - With the pinpoint ones like yours - your idea of just sanding off the tops is what is actually done. Use a fairly large board/plank type - I like a 4 x 6 piece of plastic board (e.g. Kingboard or Starboard) and attach/wrap a fine grade sanding paper to it. Then gently track back and forth over the little buggers to reduce them to the existing level of the rest of the good gelcoat. The idea is to not sand down into the good existing gelcoat or to make "dished" depressions into the gelcoat - just get rid of the tops.


What grit sandpaper is recomended?


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## mitiempo (Sep 19, 2008)

osirissail
This sailor has a more artistic friend. 
Brian


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## osirissail (Oct 27, 2009)

- - Try to get automobile refinishing sandpapers - not the hardware store stuff. Find a automobile paint supply store and get your sandpaper there. 
- - It comes on two types - dry and wet sanding. You can start with 120 grit dry paper to knock down the tops of the blisters. Then progress to 220 and 320 using each to only remove the previous papers "gouges/sanding marks". Then switch to wet paper in 500 and then 800 - only if you want a very fine surface. You use water to keep from "burning/melting" the gelcoat with the finer grit papers. But normally you can skip the 500 & 800 if you are going to paint rather than apply new gelcoat.
- - If there are obvious craters, then some epoxy putty might be used, otherwise use "hi-build" primer that is recommended for the brand of paint you are going to use. Different brand paints have different chemical properties and it is not wise to mix brands. Stick to one paint manufacturer/brand name of paint.
- - If you are looking for the finest, longest lasting, then AwlGrip is the top of the line. But AwlGrip is very complicated and requires an assortment of up to 5 different parts/additives to get the proper mix. However, it can be very successfully applied with a roller or paint brushes. It takes two people to do it using a technique called "roll and tip/brush." One person rolls on the paint and immediately behind is the second person with a real quality brush smoothing the roller stipples with the brush. Done right it comes out looking as fine as a spray paint job. 
- - However, other paints will look just as good - for a shorter period of time. They do not "wear" as well as AwlGrip but on the other hand they are much easier to use and very much more economical. There is no sense in putting a $10K paint job on a $5K boat. 
- - The secret to the finest looking finish - using any of the paints - is the technique of getting the thickness of the paint correct using the various thinners. The paint needs to be thick enough to cover and not run on a vertical surface and at the same time thin enough to allow the paint to "settle" to a glass surface. 
- -That is why I suggested the "artist" type graphics job. Both to hide the gouges and other disfigurations left by previous owners, and to to eliminate as much as possible large areas of single color surfaces which tend to show underlying problems a lot easier than a every changing paint design. And it is just a lot of fun having a "different" boat rather than the boring white and blue boats. The "artistic" is sometimes called "super-graphics" as the design is rather large.


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## superiorvoyager (Jan 3, 2009)

Thanks, What about spraying the finish. I have a friend who is great with a spray gun (commercial painter) and has said if he is around in the spring is I supply materials and do all the prep work he would spray it for me. I live in an area with 40-60% unemployment so most people travel out of the region for months at a time for work so he could be anywhere on a contract at that time.


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## cutterorient (Feb 22, 2009)

Last december I paid two monkeys to soda blast all my bottom paint off - god knows how many years worth. One thing that was revealed were tons of little holes varying in size from a pinhole to say 1/4 inch. And it sounds similar to what you may have. The blasting had taken out the material creating a 'lunar' surface. But they did not seem to be blisters in the tradition sense. There was no liquid that came out nor moisture readings different from any other area that was ship shape. I named them 'gel coat irregularities'. I am no chemist but assume there was something amiss when they originally sprayed the mold, or a reaction with a paint, or expansion / contraction problems under paint, or the gods were angry, etc.

I let it sit in cold, dry winter air for a few months and them set about filling all 25,000 of them with thickened epoxy. Wait for favorable temperatures for this.

After this and other repairs were done I rolled on 6 coats of unthickened (although I tinted it grey except for the rudder ) epoxy for a nice barrier coat.
I tried to post some pics but they are too high res.


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## cutterorient (Feb 22, 2009)

I guess the pix worked so here are a few more; if this is what you have its not a big deal, just tons of work.


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## superiorvoyager (Jan 3, 2009)

I tried sanding a little section with a shooting board and it seems to work great took the bumps down quite quick. So I'll sand those down and then fill the nicks and scrapes then fill and fair those. The problem I can see in getting ready to paint will be removing the stripes that were painted on over the gel coat. They were painted with enamel paint and as soon as the sand paper hits those it clogs right up. Any easier way to remove the old paint?


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## RichH (Jul 10, 2000)

superiorvoyager said:


> Thanks, What about spraying the finish. I have a friend who is great with a spray gun (commercial painter) and has said if he is around in the spring is I supply materials and do all the prep work he would spray it for me. I live in an area with 40-60% unemployment so most people travel out of the region for months at a time for work so he could be anywhere on a contract at that time.


Interlux Perfection, etc. are great for 'roll & tipping' .... but to attain a decent job you must match the amount of thinner exactly to the days conditions of temperature and humidity (for each side of the boat you are painting). Don Casey has published a method of roll and tipping using precise thinner additions that can produce very acceptable results ---- do websearch: "Don Casey" + "roll and tip". Still, if you havent performed 'roll and tipping', you should 'practice' and develop your technique on an old dinghy, etc. before you attempt your first large job, as the learning curve is steep.

Spraying such can be dangerous due to the small aerosols that contain isocyanates (same stuff that killed a few thousand people in Bhopal, India a few decades back). Interlux recommends a SCBA (full suit breathing apparatus ... and you will sweat to death in one) but for myself and others who have 'shot' Perfection we just wear 'multiple stage aerosol coalescing' masks and 'stay strictly upwind of the spray while we hold our breaths for a very long time' - very very risky. These paints are unlike and very different from the common automotive paints where all you need is a simple NIOSH rated vapor mask --- and vapor masks do a very poor job of retaining very small aerosols. 
Obviously, most marinas will not let you DIY spray these finishes due to the risk of overspray to other boats and the 'health risks' involved. If you do spray Interlux Perfection be SURE that you get the full technical manual - order direct from Interlux ... will save a lot of grief.

;-)


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## RichH (Jul 10, 2000)

superiorvoyager said:


> ......... They were painted with enamel paint and as soon as the sand paper hits those it clogs right up. Any easier way to remove the old paint?


WET & dry sandpaper, using a wee bit of dishwashing detergent in the water to help keep the grit from clogging. Keep the sandpaper WET with the soapy water.

If you need to DRY sand, then use a 'production grade' / 'open coat' paper ... will have lots of spaces where there is NO grit - wont 'clog up' so fast.


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## osirissail (Oct 27, 2009)

superiorvoyager said:


> I tried sanding a little section with a shooting board and it seems to work great took the bumps down quite quick. So I'll sand those down and then fill the nicks and scrapes then fill and fair those. The problem I can see in getting ready to paint will be removing the stripes that were painted on over the gel coat. They were painted with enamel paint and as soon as the sand paper hits those it clogs right up. Any easier way to remove the old paint?


Try using commercial / hardware store paint removers. If it is normal house paint or typical enamel paint it comes off with the paint strippers. Look for the strippers with high percent of methylene chloride - which is a very toxic, brain dissolving chemical so wear a "mine safety - organic fumes" respirator which you should have anyway for any painting especially spray painting.
- - If you friend is a professional spray painter, see if he has a HVLP type spray gun of very good quality like a "MACH 1". It is a very expensive type gun and also he should have at least two water separator devices/filters on the compressed air. Water and sprayed paint does not work especially with the high end topside paints. If he is familiar with spray painting automobile finishes then you have hit paydirt. The techniques and chemistry are almost identical.


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## superiorvoyager (Jan 3, 2009)

If the weather holds I'll try some paint stripper and do some sanding. My friend used to run an automotive paint shop but now does mainly just commercial work (Industrial equipment etc) so he either has or has access to all the equipment. I*f he is away I have a number of other friends with equipment and automotive experience but they are just backyard mechanics.


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## osirissail (Oct 27, 2009)

- - They should be able to do a magnificent job if they have experience and the equipment for doing auto refinishing. If you go that route the preparation work before they show up with their HVLP gun will make a significant different in the final product. Sanding, cleaning, fairing, filling, and sanding and then applying Hi-build primer and sanding that smooth is very important and time consuming as we tend to be perfectionists about our own boats.
- - Sssh! don't tell anybody but the "super-secret" to long life and a "world-class" finish is: after the pigmented coats are applied to the boat - apply two layers of "clear-coat". Clear-coat is the exact same paint as the pigmented (colored) paint except the manufacturer has left out the pigment. You apply two layers of clear paint over the pigmented paint. This gives a deep glass-like depth to the color and more importantly as the paint weathers the non-pigmented paint wears away before you get to the colored paint. The colored paint will change color to lighter shades as the sun and abrasive particles in the atmosphere wear down the surface.


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## osirissail (Oct 27, 2009)

cutter orient - - sand blasting, soda blasting is well known to cause those little craters you got. As with any material, organic or man-made there are hard areas and soft areas and the "blasting" eats away the soft areas. Wood carvers use sand blasting to get wonderful "wood grain" relief in their sculptures.
- - The skill and care (interest) of the person using the sand/soda/shell blaster makes all the difference between removing the paint only - or removing a lot of the hull/gelcoat. I always personally supervise any hull blasting and usually give the worker a generous "tip" beforehand to insure that he takes particular interest in controlling the equipment to minimize over-blasting. Then you do not have to spend days of work patching up the craters he made.


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## mrybas (Jun 23, 2008)

osirissail- Wouldn't these craters left behind after blasting be the areas that were previously blistered/not bonded to the underlying laminate? Therefore, a good thing that the areas of compromised gelcoat removed?


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## osirissail (Oct 27, 2009)

Not really, 'blasting' is not uniform. The air pressure and material ejection from the gun along with variable distances from gun nozzle to hull results in areas getting too much "blasting" and other areas being inadequately blasted. Add in the reality that FRG hulls are not perfectly uniform in resin mixture and gelcoat depth. So these little craters result. 
-- A previously "patched" hull after blasting will show the "hard spots" where filling and repairing occurred. If you had massive amounts of gel-coat blisters then "peeling" would be appropriate rather than blasting. 
- - Since gel-coal blisters are not a structural problem there are "quick and dirty" fixes and more involved "proper" repairs available. Racing boats would be more concerned with restoring a super-smooth surface, whereas cruisers would only want the craters filled and a barrier coating to stop new craters.
- - The major consideration in any FRG process is getting sufficient absorbed water out of the hull before applying new resin. Insufficiently dried hulls will see the little "filled craters" drop out again as they never got a proper grip on the underlying hull.


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## mintcakekeith (Nov 5, 2009)

Not entirely relevant but I believe there is a method of blasting using dry ice which is much kinder to the underlying surface. K


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## superiorvoyager (Jan 3, 2009)

To give an update. I sanded the whole hull down (I did use an orbital sander which worked quite well) which opened most of the blisters. I then picked ope the ones that weren't sanded through.Then I used westsystem, sanded again, then epoxy Prime Coat followed by three coats of perfection rolled and tipped. It was of course a lot of work and unfortunately the weather was so unpredictable this summer with high winds, high humidity, constantly changing and never as predicted. Not a perfect Job but most people at my marina thought I had a new boat. Up close (2-3 feet) you could tell it wasn't sprayed but who besides me looks that close. Thanks for all the help.


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## superiorvoyager (Jan 3, 2009)

I'll try to post a picture or two but I really didn't take many this summer.


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## Stillraining (Jan 11, 2008)

Looks Nice.


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## superiorvoyager (Jan 3, 2009)

Thanks, still have to put the name on but We just wanted to get it in the water this summer. Next spring we will put the name on. It sure was a lot of work but considering the quotes I had to have it done I don't mind.


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## mitiempo (Sep 19, 2008)

Good looking boat.


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