has any one tried thinned polyester to treat wood?

[UseDaGreyMatter]

Someone mentioned that you use polyester thinned with acetone for the first layer. I was researching this to get details and found this site.
http://www.hares.net/boat/waterproofing.htm

has any one ever tried this and if so would you please share specific details. I'm redoing the v berth and want to put some sort of protection between the hull and bed.

Barb

 

[Bob J.]

I coated the new stringers & compression post "step" with polyester resin prior to glassing them in the bilge. I didn't thin the resin, just painted the stuff on. Not sure if it's the right thing to do but it made me feel better about putting wood back into a bilge.

Bob

 

[CharlieCobra]

Acetone and polyester resin together is a recipe for a fire. Don't ask me how I know this....

 

[Tribu336]

Diluting polyester with acetone is fine. I recently took a course on fiberglass repairs and using diluted polyester resin (with the right proportion of catalyst of course) is the best method for protecting a piece of wood before it is glassed in. The first coat is diluted 50/50 and the second coat is diluted 75/25 (polyester/acetone). The diluted resin penetrates the fibers of the wood and makes a waterproof barrier.

Good luck.

 

[Cool Beans]

I don't see why not, though I prefer Epoxy to seal wood. Mostly because I feel Poly kicks off to fast and doesn't get a chance to soak in. . .but any protection is better than none

 

[Ross]

It all depends on how you catalyse it batch. That is the nice thing about ester resin you can control the gel time.

 

[Ed A]

but it will also crack if the wood flexes. I way prefer epoxy. here is a neat trick.
Epoxy coat the wood then varnish it. Looks like glass with some uv protection from the varnish..(not for the v berth.)

 

[Snotter]

It isn't recommended to use epoxy on wood that will be bonded with fresh polyester resin.

 

[UseDaGreyMatter]

Doing the Happy Dance!!!!

well I got brave and went ahead with it. Started out with doing the underside of the tip of the v berth. Used the extra to seal the ends of the large piece, knot holes etc. Read a LOT of different ratios. Used acetone. Decided to start with a 4:1 ratio and go down from there. I did a 4:1 , a 2:1 then a 1.5:1 ( my hand slipped) then straight poly and cloth. Looked at it last night. Except for a few imperfections of something that got stuck and sticks up, I did not notice, the fact it is not perfectly level and the beveled edges stuck to the plastic that I had under the wood and what I think might be a few air bubbles. it don't look to bad for a rank beginner IMHO. Will post pics on my blog hopefully Saturday. It definitely looks a LOT better then the first one I did of just putting the poly on with out pre-coating it.


FYI I knew I was low on hardener. I called Bondo, turns out 3 m has bought them out. Asked the guy if the regular hardener I could buy locally at the automotive store would work with the "waterproof" resin ( not the regular resin they sell for auto body work). He said as long as it is any 3m or bondo liquid hardener or any liquid MEK hardener it would work. He made a BIG point about NOT using the creme hardener! Got some at Oreillys. 1 point something ounces for about 7.00 with tax.

Have to revamp the work area. Think I'm going to put newspaper under the piece and raise the wood up on something to prevent the cloth from attaching itself to the plastic. Will probably use some of these plastic containers food comes in.

Other then that I'm a happy camper. Plan on doing the large part this weekend if I can get around to it. :dance:

It absolutely amazes me how all the stuff I learned in the kitchen is sure coming in handy while figuring out how to work on this boat.
Barb

 

[Ross]

Re: Doing the Happy Dance!!!!

Get a 10 or 12 CC syringe and needle and use that to measure the hardener. One cup of resin is about 250 CC's so 1 % catilyst will be 2.5 CC's . More accurate and gives very consistant gel times. On cold days you can use a little higher percentage and on very warm days a bit lower with 2 % about the upper limit.

 

[RichBone]

If you're coating bare wood do it with stable or falling ambient temps. If the temp raises during the cure you could get out-gassing from air coming out of the wood.

Rich

 

[Dave Groshong]

do yourself a favor and use penetrating epoxy, then epoxy resin for laying any cloth or laminating

 

[woodster]

do yourself a favor and use penetrating epoxy, then epoxy resin for laying any cloth or laminating

"BINGO"

regards

woody

 

[UseDaGreyMatter]

Conclusion

Well all of those are really great ideas. I already have the poly. It was given to me as a sample. I had the pieces already done sitting our side. It started raining a bit ago. I went out to see what they looked like and while wet there are no water spots. The pretreated looks great compared with the non pretreated. If the non pretreated was going below the water line even I would have to say it will laminate. I did a really crappy job if you compare it to someone with more experience. But for a rank beginner I did not do to bad/ Now there is no way I would use poly below the waterline on boat that was in a slip or long term cruising, but for my purposes it works. I realize there are a lot of folks out there that are very pro epoxy. If you can afford it great. My priority is "get er done" so I can sail. Not spend months saving up to buy epoxy.
I have made one very important decision though, Unless I have a shop to work in there is no way I am building a wood boat that gets glassed.
And yes, in that event I would use the epoxy.

Barb

 

[UseDaGreyMatter]

If you're coating bare wood do it with stable or falling ambient temps. If the temp raises during the cure you could get out-gassing from air coming out of the wood.

Rich

WOW I never read about that!!!!!!
THANKS for the tip!!!!!!
Translated to: do it after the outside temps have already reached the high for the day. Got it!

Barb

 

[UseDaGreyMatter]

Get a 10 or 12 CC syringe and needle and use that to measure the hardener. One cup of resin is about 250 CC's so 1 % catilyst will be 2.5 CC's . More accurate and gives very consistant gel times. On cold days you can use a little higher percentage and on very warm days a bit lower with 2 % about the upper limit.

Good idea. Thanks

Barb :dance:

 

[kendall]

do yourself a favor and use penetrating epoxy, then epoxy resin for laying any cloth or laminating

The advantages epoxy holds over polyester is well known, However there are many applications where you simply don't need the extra strength and cost.

You don't need a 1/2 inch stainless steel lag screw to hang a picture, a finishing nail is more than strong enough.

 

[Ross]

If durable wood species were used the rest of the discussion would be moot.

 

[doehunter]

When they build a boat, they lay it up using glass and polyester resin. (don't they??)
The strength comes from the saturated glass, not the resin itself.
So when making mods to a fiberglass boat, why would you use epoxy. It seems like the poly would bond to existing older poly better than another compound.
Jim

 

[Ross]

When they build a boat, they lay it up using glass and polyester resin. (don't they??)
The strength comes from the saturated glass, not the resin itself.
So when making mods to a fiberglass boat, why would you use epoxy. It seems like the poly would bond to existing older poly better than another compound.
Jim

Epoxy bonds are stronger than polyester bonds but polyester bonds are strong enough. Making new bonds in old work requires a little extra care to get them right.