# Making fiberglass panels



## peterchech (Sep 2, 2011)

For purposes of making shelves and bulkheads out of solid glass, what is the recommended most cost effective method of fabricating glass panels, say 1/4 inch thick?

A friend of mine told me he uses a few layers of thick fiberglass mat with thin epoxy resin, sandwiched in between two pieces of plywood with some cinder blocks on top to get even pressure and some squeeze out. He uses wax paper as a "mold release" between the ply and the glass.

How good is this for making panels? Should some roving or else woven glass layers be incorporated between or on the outside of the mat? Can a mat only layup work with, say, polyester resin?

I'm just looking for the most time and cost effective method of fabricating stiff fiberglass panels. I may use them for structural support, or also to make a dockbox for my slip.

Google isn't being much help...


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## deniseO30 (Nov 27, 2006)

it's labor intensive given the fact you can buy .. possibly even cheaper then making them yourself. But if you insist, Vacuum bagging would be the best way, plywood encapsulated is best, there's foam core too. Thickness is more important then the covering. imho, I just feel the cost is and the benefit is low. Marine plywood alone is pretty reliable stuff by the way!


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## bljones (Oct 13, 2008)

How big do you want your panels to be?


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## peterchech (Sep 2, 2011)

For quarter bulkheads, and for a dock box, so 4X4 will work


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## hellosailor (Apr 11, 2006)

What Denise said.

Simply laying up thick masses of fiberglass is a bit crude. Wastes materials, adds dead weight, might be easy but there are so many better ways to do it.


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## peterchech (Sep 2, 2011)

hellosailor said:


> What Denise said.
> 
> Simply laying up thick masses of fiberglass is a bit crude. Wastes materials, adds dead weight, might be easy but there are so many better ways to do it.


List 'em

vacuum is difficult to do on flat panels, and requires me to take apart an old refrigerator and figure out how to turn it into a vacuum... a simple how-to, or a link to a how-to would be so helpful as I've never laminated a non-cored glass panel before


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## hellosailor (Apr 11, 2006)

"and requires me to take apart an old refrigerator and "
 Ah, no, you can simply buy a vacuum pump. Either electric or manual, such as used to bleed brakes. Or a vacuum cleaner. There are plenty of web pages about DIY vacuum bagging.
You might start by checking the FAQs or calling support at West Systems and asking them the best way to go about those projects.
But if I needed a shelf...I'd either buy a shelf, or buy honeycomb or corrugated cardboard and skin it over, to keep down the dead weight.
Why use 1940's technology in 2012? Resin hasn't been cheap in decades.


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## deniseO30 (Nov 27, 2006)

Well, plywood is already a laminate, so just a covering of cloth (6oz) is most common would work. additional layers of glass really add weight and the plywood does most of the work. this link for building tanks is about the same as building a box. EPOXYWORKS Don't forget epoxy degrades in sun very quickly. so it will need protection on the outside. 
This is about the same as building a dock box How to Build a Truck Tool Box | eHow.com


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## Sabreman (Sep 23, 2006)

I've done this job several times for different purposes. IMO, ther are better ways to make a panel and solid glass ones should only be done for very specific reasons (e.g., constant immersion, high stress). A solid glass or epoxy panel is probably the most expensive, heavy way to go. As others have said, a marine ply panel that's epoxy encapsulated is faster, cheaper and easier to fabricate.

If you insist on a solid panel, the easiest way is to: 
1. get a sheet of ply and cover w/ wax paper
2. Lay out a sheet of heavy roving 1" larger than needed on all edges
3. Wet the roving with epoxy enough to wet it, avoiding puddles, squeegee off the excess. less is better
4. let dry until tacky or hard. Full cure is not necessary.
5. repeat #2, #3, #4 until the desired thickness is attained
6. Pull the panel off the plywood and sand both sides until smooth
7. Mix epoxy with colloidal silica or other filler to form a paste and spread over indentations
8. Sand smooth
9. Trim the panel to size

Congratulations. The panel took forever to make, but will hold up. I made one (12" x 18") with this process for my anchor well because it's constantly wet in there.


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## SloopJonB (Jun 6, 2011)

My first question is why epoxy? In the situations described it would seem to be a needless expense. Blisters aren't likely to be a problem and secondary bonds aren't involved so why not use plain old polyester resin - it's a LOT cheaper.

Another choice for a "mould" is to use ply or particleboard that has a smooth arborite facing. If you wax it heavily to ensure separation of the moulded piece it will give you a nicely finished panel with one "perfect" side. You could even put gelcoat down first and end up with a pre-finished panel when the laminating is complete. 

If a flat panel is all you want though, Denise is correct - why bother? Just buy some appropriately sized pre-made panel - I think it's called G10 down there.


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## mitiempo (Sep 19, 2008)

Peter

That's a lot of trouble for making bulkheads or shelves that are both heavier than plywood and not as strong if you use mat. Mat is best as a layer between roving layers to fill the weave.Expensive as well as very time consuming. 

Good plywood - marine or not - is fine for shelves and partial bulkheads that are probably not structural.

Fiberglass - solid not cored - will be very heavy to get much strength in a flat panel. 

I do not know of any builders - production or custom - that have made flat panels out of solid fiberglass. 

Google probably isn't much help because it hasn't been done.


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## peterchech (Sep 2, 2011)

I may just go with foam core for the structural stuff, since so many here seem to think solid panels are a waste... I wonder if the foam is ultimately cheaper than solid GRP since you use less glass and resin in the end anyway...

Sure ply is easiest, and I've done LOTS of laminating of ply, but as a person who does alot of work on old boats I am well aware of its tendency to rot...


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## mitiempo (Sep 19, 2008)

The price will depend on which foam you use. Coosa is about $300 for a 4 x 8 sheet 1/2" thick. 

While I think solid glass is too heavy I don't think foam cored is necessary either. 

Treated properly with epoxy on the edges that meet the hull there is no reason for plywood to rot except through long term neglect.


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## CarbonSink62 (Sep 29, 2011)

Back when I built FG boats (well over half a lifetime ago) we used to make the decks on molds that were lined with formica. The molds were maybe six feet wide; over 30 feet long and had a camber to match the decks. We would coat them with mold release wax and build the decks from the top (gelcoat) to the bottom (FG/balsa core/FG) and then flip them rightside up.

We had a side project that involved making FG panels and we made them on the deck molds:
1. Coat a 2'x6' area with wax.
2. Paint that with a roller full of resin.
3. Lay down a 2x6 piece of mat.
4. Paint that with resin.
5. Use an 'air roller' to get the bubbles out.

Once the resin kicked off you could peel the panels off the mold and lay down more.

If you forget the mold release wax, your only option is to fake your own death.


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## Lake Superior Sailor (Aug 23, 2011)

I have used Fiberglass shower stalls ,bath tubs & truck toppers as a source for panels to build many things using fast dry epoxy glue to hold them togather untill the epoxy & glass sets up. I have just finished a motor cover for my inboard...Dale


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## SloopJonB (Jun 6, 2011)

mitiempo said:


> The price will depend on which foam you use. Coosa is about $300 for a 4 x 8 sheet 1/2" thick.
> 
> While I think solid glass is too heavy I don't think foam cored is necessary either.
> 
> Treated properly with epoxy on the edges that meet the hull there is no reason for plywood to rot except through long term neglect.


Miti has it right IMHO - almost all boats have interiors that are largely ply. The only exceptions I can think of offhand are the extreme race boats that have all fiberglass interiors.

Seal coat the ply with epoxy and it will be essentially as rot proof as solid glass and a LOT cheaper, lighter and easier to make.


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