epoxy resin laminating plywood floor panel

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tfret

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I am ready to laminate a newly cut floor panel and need some advice. I've read on other posts to thin the epoxy with alcohol for the first couple coats to improve penetration. Then straight epoxy on the last coat. But do I add any hardener to the epoxy at all, or go without? The Bondo brand resin I bought says work time is about 10 minutes before the hardener sets up. That might not be enough time to finish brushing the entire board, and this stuff is too pricey to waste. If I don't use any hardener I'm not sure the epoxy will cure at all. What do I need to do?
 
If you don't add the hardener the epoxy will never cure and you'll have a big mess to clean up. 10 minutes is too short a time (IMHO) to coat a large piece of ply. I'm not sure about thinning your brand of epoxy, does the mfgr recommend a thinner? IIRC Your short cure time won't soak in very much before it kicks. There are other epoxies with longer working time that would be more suited to your requirements. Can you take it back and get another brand with longer curing time and maybe a little less viscous?

Here's a link to thinning epoxy from West systems. http://216.219.217.157/skunkworks/Glues/WestSystem/Thinning/Thinning.html
 
If it is Bondo, are you sure it is epoxy & not polyester? If polyester, I don't think you use acohol, if epoxy, you only thin the first coat & then put the second coat on before the first coat dries hard.
Al
 
I've never "thinned" epoxy. YOu can select epoxy and get one that is formulated to me more liquid,, but you do not thin it.

And all epoxies use a very specific quantity of hardnwer to resin. If you wish to change the set time, you change the type of hardner.

One last thought: You do not need to thin the epoxy at all...
 
Are you merely trying to waterproof a piece of plywood or are you attempting to do something else?

If you're planning to waterproof a sheet I would begin by using marine grade plywood, since it is bonded together by waterproof resin and will not delaminate if it is subjected to moisture. Standard plywood will delaminate if it is subjected to moisture.

Secondly, I would buy a low viscosity epoxy with an extended cure schedule and not worry about trying to thin it with a solvent. I don't see any advantage to thinning the product and see more potential for an inconsistent mix. The low viscosity will allow the plywood to absorb a sufficient of product and the extended cure schedule will give you enough working time.

Bob
 
Bondo and other similar fillers are polyester resins - different chemistry and application. For epoxies, whatever brand you use, read and heed Radioactive's advice. Get the right epoxy for the job you are doing and then follow the instructions explicitly. With the right epoxy you will not need to be concerned about improving penetration. Generally, you do not want to thin epoxies, but it can be done with small (less than 10%, less is better) inert solvent addition. Solvent thinning has it own consequences. Cure schedule (working time) should preferably be determined by the type of hardener rather than the amount.

You say you are laminating, but it sounds more like you are coating. What exactly are you doing and what are you trying to accomplish? Where does the Bondo come in ?
 
I am water proofing the board, so I guess I am actually coating and not laminating. Sorry for the terminology mis-use, I'm on a learning curve. So, to water proof, or coat the plywood maybe the Bondo product isn't the best choice. I kept the reciept just for that reason and feel sure I can return it. Can someone recommend the proper product and procedure for me?
 
I suggest you spend some time on the West Systems website -- google West Systems Epoxy. For a floor panel I believe an epoxy top coated with a UV resistant varnish would be the most durable choice. Spend some time in their section on Using West System Epoxy, and also look through the Projects section. Look for articles and How To's on protecting wood.

I believe you will find that what you want for an epoxy will be West 105 resin and 207 Special Coating Hardener. This will be your epoxy sealer system. Then it should be top-coated with a UV resistant marine grade exterior varnish. See the articles under Projects then Techniques and Materials.
 
I also agree with Eric. Epoxy is great stuff, but finicky. You must use the exact amount of hardener specified and thinning it doesn't work very well like polyesther resin. Also, epoxy is very vulnerable to UV, so you must protect it with some UV resistant coating, like awlgrip. Make a practice sample on a piece of scrap to get the hang of it. Fiberglast dot com has good supplies and information...can be a bit pricey, but they will be very helpful.
 
I've seen way to many cases of polyester checking & lifting off of wood, especially plywood. Epoxy, number one is an adhesive. If you protect it from UV rays, it is on there for good.
Al
 
Check out this site: rotdoctor dot com. They sell epoxies specially formulated to seal wood, etc.
 
One other question. The deck is carpeted, as the new section will be. Do I still need to apply an UV inhibitor since it will be under the carpet?
 
No, you really don't need the UV inhibitor for something that goes under carpet but it comes with most of the top line varnishes anyway.

There is an economical alternative to using penetrating epoxy on marine plywood and I've had good time-tested experience with it.

This is all you need with an above the waterline application like this. Treat the marine plywood with several coats of Pettit Clear Sealer. This stuff has a lot of purposes, but it was originally formulated for sealing marine plywood in the days before epoxy.

Dry-fit the panel and drill out any fastener holes first so you can give all of the surface (including edges and fastener holes) a good soaking. I'd slosh on by brush at least two coats of unthinned Pettit Clear Sealer, maybe three.

Once the clear sealer has cured (2 coats a day is typical) give the plywood a couple of coats of marine oil-based exterior enamel paint (one coat per day, usually). In your application that finish will be rot and wear proof for darn near forever. Put the carpeting over it when done.
 
quote:
Originally posted by tfret

One other question. The deck is carpeted, as the new section will be. Do I still need to apply an UV inhibitor since it will be under the carpet?

Click to expand...


That changes things a bit. I would probably choose paint, as yzer suggested, for a topcoat under carpet.

Here's the basic drill - seal the wood, then apply a protective topcoat. Paint will last longer than varnish, and if you re carpeted over top there is no need for the clear wood look.

If you used marine plywood, and I hope you did on a carpeted floor boards, then a conventional marine-grade sealer should be good under paint. If you didn't use marine plywood, then for now I would still go with the epoxy with extra attention to the panel edges (maybe an extra coat or two there), then paint.
 
Going under carpet I would be even more apt to use epoxy. I believe that the carpet would hold moisture in & eventually work under the paint. I'm not a chemist, so that is just my $.03 worth of opinion.
Al
 
Those oil-based marine coatings will work for you on marine plywood. They will save you some time and money, too. You might want to give it fresh recoat of paint 10 years from now, probably not.
 
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