# Help choosing my barrier coat system: Interprotect vs. West System vs. Other?



## Beersmith (Nov 5, 2008)

After stripping off all of the gelcoat below the waterline, grinding out blisters, and drying the hull for about 8 months; I am nearing the time where I will begin to repair, fair, barrier coat and paint.

I am trying to figure out which products I will be using so I can cost out the whole thing and get organized. I have some questions regarding which brands/systems I should go with at each stage. I am trying to pick the best product for each stage of the bottom job, but I keep reading that I should stick with one system (such as Interlux from fairing all the way to paint). But I also see products like West System or System Three that would require me to use another brand for paint...so a full bottom job with one brand might not be necessary. 

For filling, fairing and repairing I had intended on using West System or US Composites epoxy with the necessary fillers for the job. (edit: and I just now discovered Interlux Epiglass to add to the confusion) I will need to do a lot of fairing on the bottom, so would West System be a good choice or should I consider a product like System Three Quickfair, or Interlux Interprotect Watertite Epoxy Filler?

I then intend to add a barrier coat using either West System epoxy + barrier coat filler; or the Interlux Interprotect system. What are the advantages/disadvantages of each barrier coat system? I see many people using Interprotect around the boat yard, but since I will be buying a ton of epoxy for the fairing job and for other uses around the boat I don't see why I shouldn't just use West System barrier coat filler for the job. Is it an inferior product for protecting against water intrusion? I am a little skeptical due to the overwhelming use of Interprotect. 

As for bottom paint...I'll come to that at another time and will probably ask around the local area for what works best. I am more concerned about the fairing and barrier coat right now. I just don't want to do a bad job because it cost less (hypothetically) to use System Three fairing, West System barrier coat, then Interlux bottom paint; only to find that the three don't work well together.


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## T37Chef (Oct 9, 2006)

I used the Petitt product, see more here: http://www.sailnet.com/forums/322678-post.html


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## harbin2 (Jul 5, 2008)

I don't have the experience of many others here but I did what you are doing two years ago and I'll give you my comments. The boat had a West barrier coat from about 8 years ago (by a PO). I removed some of it and applied 2 coats of Interprotect. I liked the way it mixed and went on. I also liked the color (I used white). I was able to get it discounted. I did little fairing but what I did, I used MAS. I like West products but the MAS is easier to mix in small quantities since it is a 2 to 1 ratio (no pumps, etc.). I did use an Interlux paint but I find it hard to believe the brand of epoxy, barrier coat, and paint makes much of a difference. I feel for the work you have done - especially if you did it yourself - like I did. I have been happy with the results.
harbin2
Islander 30


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## sailingfool (Apr 17, 2000)

I would not worry about different products working together as long as you read and follow their prep rules.

You should use the right product for each job.

Use the Interlux Watertite for divot filling, two layers, the first a rough fill, the second a careful level fill, as it is a bear to sand.

Use West epoxy with microballoons for fairing as it's very easy to spread and sand.

Interprotect 2000 is specialized for barrier coating, it set ups slowly and is easy to roll. West does not make a barrier coating product, although their epoxy doubtlessly makes an excellent barrier coat - if you can get it not to cook up fast, and develop a good roller routine. I have to admit, I never tried to overcome these challenges, the Interprotect to too good at it what it does to struggle with regular epoxy.


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## sailingdog (Mar 19, 2006)

If you use West Systems epoxy and microballoons for the filler, don't forget to coat it with a layer of unthickened epoxy or the microballoons can absorb water. As for the barrier coat, I'd recommend going with Interprotect 2000E.

From a post I wrote previously on applying Interprotect...



sailingdog said:


> Alternating the colors helps a lot with determining where you've painted, but it is also very useful for helping you coat the areas around the boat stands. For instance:
> 
> The first layer is gray, since the gelcoat is white, and you can paint right up to the boat stand pads. Then you paint a layer of white, and leave about a two-inch margin of gray paint around the pads... then paint a layer a gray and leave a four-inch margin around the pads or about two-inches of white and two inches of gray showing...and then finish with a layer of white-with a six-inch margin around the pads-with two inches of gray, two inches of white and two inches of gray.
> 
> ...


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## zz4gta (Aug 15, 2007)

If you are fairing the bottom of your boat, get templates for the keel and rudder as well. This little extra step can add a tremendous amount of performace to your boat. Spend 80-90% of your effort on the foils, the other 10-20% on the rest of your bottom. Do it once, and it'll pay you back year after year. I used west systems epoxy, a little more expensive (buy the pumps if you go this route) but its simple enough to work with. I used silica for filler below the waterline. I had to build up a section of the keel and rudder, then shave 3/16" off the side of the keel. The silica as a filler is very hard to sand, use it sparingly. 

I used petite products. You need a mixing attachment on a drill to mix the barrier coat but that's not uncommon. I only wish I had sanded the last coat a bit smoother as this would've allowed the bottom paint to go on smoother. Allow proper drying time. All I did was wipe down the gelcoat with acetone, and roll on the barrier coat. 

I'm using white Vivid paint and just thinned it the max allowed and rolled it w/ 1/8" foam rollers. This year I plan to thin and roll and tip for a better/smoother finish. Spraying would be the best, but hell, you're going to re-coat next year anyway. 

Maintenance is diving on the boat with a sponge once a month until it gets warm. Then its once a week. When it starts to get chilly, I go back to twice a month, then once a month, then I say screw it when the water hits 50*.


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## tommays (Sep 9, 2008)

Everybody wants about a 20-mil thickness 

West likes there 422 barrier coat Additive and there techs that answer question on there Sailing Anchary WEST sponsored Fix It Anarchy section make a compelling argument for its use


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## Beersmith (Nov 5, 2008)

Thanks a bunch for the information everyone


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## Beersmith (Nov 5, 2008)

tommays said:


> Everybody wants about a 20-mil thickness
> 
> West likes there 422 barrier coat Additive and there techs that answer question on there Sailing Anchary WEST sponsored Fix It Anarchy section make a compelling argument for its use


well after reading this I'm still torn between West System (using 422 Barrier coat additive) or Interprotect 2000E.

Any other arguments for one or the other?


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## sailingdog (Mar 19, 2006)

Beersmith said:


> well after reading this I'm still torn between West System (using 422 Barrier coat additive) or Interprotect 2000E.
> 
> Any other arguments for one or the other?


If you use Interprotect 2000E, you can alternate the colors to make sure you get the proper coverage levels, which is more difficult to do with West system. Also, West System epoxy has amine blush issues.


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## dougshipl (Jan 22, 2007)

We're in the warm waters of FL and have been using Trinidad SR over our 2000e for years. No issues, and as noted prep and application is everything. With that said, a few years back we had an Irwin we sailed in San Francisco area and an ol salt recommended a commercial barrier product from Ameron. Its was used on the mega yachts at the time. It was less then $40 a gallon and went on almost like tar...then we followed up with Trinidad. He was right, it was cheap, thick and I don't think anything would ever get through it. It worked fine, no blisters, etc for years. I note this in event someone is on a tight budget and doesn't want to over pay for the hyped up marketing on traditional boat store products. But like I said, we've had no probs with the 2000 with Trindad SR.....except the $


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## gtod25 (Aug 5, 2000)

*Its not a decision its a choice..*

The Incredible Hull: Barrier Coat

have fun!!!


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## Beersmith (Nov 5, 2008)

Some people claim that 2000E has problems with "Orange peeling", which I have seen on boats around the yard. Does that significantly effect performance at all? My boat is a heavy displacement cutter, so I'm not terribly worried about performance, but if I loose a half knot I wouldn't be happy.


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## T37Chef (Oct 9, 2006)

sailingdog said:


> If you use Interprotect 2000E, you can alternate the colors to make sure you get the proper coverage levels



Last I looked, you can do the same with the Pettit product as well, I think white & grey are available?


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## sailingdog (Mar 19, 2006)

I doubt the barrier coat would affect your boat speed at all, especially given that you're a heavy displacement cutter design.


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## sailingdog (Mar 19, 2006)

T37Chef said:


> ​
> Last I looked, you can do the same with the Pettit product as well, I think white & grey are available?


He was discussing west systems vs. Interprotect... Pettit wasn't even a contender... read his post.


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## T37Chef (Oct 9, 2006)

Beersmith said:


> well after reading this I'm still torn between West System (using 422 Barrier coat additive) or Interprotect 2000E.
> 
> Any other arguments for one or the other?


The Pettit & Interlux barrier products are pretty much the same I think so I would probably just go with the less expensive one. The link I provided above I am using Pettit and found it to be easy to work with and has held up fine since application a few years ago now.


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## T37Chef (Oct 9, 2006)

sailingdog said:


> He was discussing west systems vs. Interprotect... Pettit wasn't even a contender... read his post.


I get that  I was clarifying there is another option besides Interlux Interprotect!!!!!!!!!!!!!!!!!


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## T37Chef (Oct 9, 2006)

Sailingdog...*In fact you yourself say something very similar here:* http://www.sailnet.com/forums/gear-maintenance/36866-barrier-coat-petit-vs-interlux.html


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## sailingdog (Mar 19, 2006)

T37Chef said:


> I get that  I was clarifying there is another option besides Interlux Interprotect!!!!!!!!!!!!!!!!!


and I was just busting your chops. :laugher


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## T37Chef (Oct 9, 2006)

Don't have time to read them myself, but here:

http://www.pettitpaint.com/fileshare/product_pds/1470122.pdf

http://www.yachtpaint.com/MPYACMDatasheets/Interprotect_2000E+eng-usa+A4+Y+20100614.pdf


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## Beersmith (Nov 5, 2008)

T37Chef said:


> Don't have time to read them myself, but here:
> 
> http://www.pettitpaint.com/fileshare/product_pds/1470122.pdf
> 
> http://www.yachtpaint.com/MPYACMDatasheets/Interprotect_2000E+eng-usa+A4+Y+20100614.pdf


thanks


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## zz4gta (Aug 15, 2007)

There will be a difference in performance between a smooth bottom and one w/ orange peel. Not a big difference, but there will be one. Just put on an extra coat of barrier, and then sand it with 80 or 120 before the bottom paint. Should knock down any lumpiness and make for a pretty smooth finish.


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## sailingfool (Apr 17, 2000)

If you are going to sand the faired areas or the bottom in total for smoothness, be sure to use a long board, see 3m Longboard, as that's the only way to remove the high points. You also need to use a long board if you actually shape your foils, which is pretty unusual outside of one-design racing.

This is an ugly and painful job best done by teenagers.


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## RichH (Jul 10, 2000)

No need to sand a 'new' barrier coat to make it smooth. 
You can apply the first coat with a roller but successive coats with a large polyethylene trowel (not a roller) and 'fill' the previous hills and valleys from the roller application. Method: roll on and immediately 'wipe' with a trowel, the semi-hard 'peaks' from the first 'roller coat' will set the height for the trowel to 'glide' on --- thus quickly filling and fairing the 'valleys'. This 'troweling' is in the same manner as applying the final gelcoat to a MALE plug mold. For perfectly smooth and faired you can finish with a thinned out fairing coat using a BIG trowel.... and the WHOLE job should be continuous so that NO layer 'fully cures' so that there is continuous bonding throughout. This can include the first bottom paint coats (hot-coating) for much better 'adhesion'.

----------------------------
The *MOST IMPORTANT* characteristic or goal of ANY barrier coat system is the MIL-THICKNESS. Without the proper mil-thickness you are vulnerable to future water (principally water vapor) permeation through the barrier coat into the FRG. With a roller you have to apply MORE barrier so that the deepest 'valley' is at the proper thickness; with a smooth or troweled-on application that required thickness is more easily controlled.

How to know that you have the proper thickness --- go to an industrial paint/coating supply and get 'mil-thickness gages'. These are 'little comb-like or 'toothed' gages' that you 'push' into the fresh/wet paint or coating and if you get discontinuous dots or dashes in the fresh surface instead of lines the thickness is too small and you need to add more paint/coating. With solvent based coatings you need to calculate the % solids so that when the solvents 'flash off' and the coating 'shrinks' you ultimately arrive at the recommended 'dry' mil thickness not the 'wet' / 'as applied' mil thickness.

Each barrier coating mfg. lists the proper 'thickness' in their 'tech manuals'. If you dont apply to the recommended (dry) mil thickness, you can expect to not have sufficient barrier applied and you will/may/can after some time observe the 'return' of the blisters/pimples. I always apply more thickness than what the mfg. recommends as I dont want to do a job 'twice' ... and barrier coating manufacturers seem to always continually 'increase' their thickness recommendations over time.

hope this helps.


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## Beersmith (Nov 5, 2008)

Thanks for this information. I am curious about the trowelling method, it seems that trowelling on successive layers would be considerably thinner than if applied by roller. Am I just overthinking it?



RichH said:


> No need to sand a 'new' barrier coat to make it smooth.
> You can apply the first coat with a roller but successive coats with a large polyethylene trowel (not a roller) and 'fill' the previous hills and valleys from the roller application. Method: roll on and immediately 'wipe' with a trowel, the semi-hard 'peaks' from the first 'roller coat' will set the height for the trowel to 'glide' on --- thus quickly filling and fairing the 'valleys'. This 'troweling' is in the same manner as applying the final gelcoat to a MALE plug mold. For perfectly smooth you can finish with a thinned out fairing coat .... and the WHOLE job should be continuous so that NO layer 'fully cures' so that there is continuous bonding throughout. This can include the first bottom paint coats (hot-coating) for much better 'adhesion'.
> 
> ----------------------------
> ...


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## RichH (Jul 10, 2000)

No, the peaks and pimple-tops from the previous 'roll coat' set the depth, the trowel 'rides' on top of the previous peaks. Usually takes 2-3 trowel applications to get the barrier smooth. You dont want to knock-down the first/previous 'pimples' with a trowel as they set the height for the trowel to fill. If you find that youre not 'thick enough' add another 'roll coat' and let partly cure. 

You can apply bottom paint in the same way ... and you get a smoothness equivalent to 'almost as smooth as a babies ass'. Smooth surfaces have less adhesion for 'growth' ... and 'release' faster and more completely when at speed - less 'roughness' for the crap to 'stick to'. With smooth applied ablatives you also get longer life as the 'total' surface area exposed is at a minimum - somewhat important if you seen the latest prices for ablatives.


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## engele (Nov 26, 2006)

*Could not be more true*



sailingfool said:


> This is an ugly and painful job best done by teenagers.


I can verify the truth of this. After spending many many hours with a longboard I passed the hat (and the respirator) to a broke teen in need of work, and it was the best spent $200 I have ever made (our agreement was for $100, but I couldn't do it when payday came. We were both happy).


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## Beersmith (Nov 5, 2008)

West System describes applying the barrier coat using a roller, then tipping off with a piece of cut up roller to smooth out the application. Would this method work just as well with Interlux, Pettit, or whatever product I use? Or even tipping off with a brush to avoid the orange peel?

Such as described here: Barrier Coating


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## sailingdog (Mar 19, 2006)

I don't see why it shouldn't.


Beersmith said:


> West System describes applying the barrier coat using a roller, then tipping off with a piece of cut up roller to smooth out the application. Would this method work just as well with Interlux, Pettit, or whatever product I use? Or even tipping off with a brush to avoid the orange peel?
> 
> Such as described here: Barrier Coating


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## RichH (Jul 10, 2000)

Beersmith said:


> West System describes applying the barrier coat using a roller, then tipping off with a piece of cut up roller to smooth out the application. Would this method work just as well with Interlux, Pettit, or whatever product I use? Or even tipping off with a brush to avoid the orange peel?
> 
> Such as described here: Barrier Coating


The hotter the day and the hotter the hull, the less chance of 'flow out' when dragging a cut roller; and, if youre 'late' or delayed in tipping out you can get 'tears', etc. in the surface. So, if youre going to use the 'tip with roller' method, you cant do this on the whole hull side and the barrier will start to 'kick' before you are finished tipping when its 'warm' outside.

The polyethylene trowel 'forces' the flow-out.


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