polyester resin w/o glass

[angib]

Arne,

Yes, epoxy is better than polyester (though also easier to get wrong). The question is whether the extra perfomance of the epoxy is actually needed for a particular job. It's really like picking hardwood .v. softwood - each has its own use.

Dave,

Mixing acetone may or may not be a good idea - it's a solvent so it will evaporate (obviously, eh? - that's why you're using it). But where it evaporates it will leave a tiny void which will then attract water, or other things, by osmosis. That's why epoxies for coating are proudly claimed to be solvent-free.

If you are putting more coats over the top, then this may not matter. But equally I have not seen any sign that it is necessary to soak resin further into the wood. Filling end grain is a different problem, where the need is to supply more resin than the capillary action can take away - the answer is repeated applications of the same batch of resin, say at one or two minute intervals, rather than several coats.

Andrew

[DestinDave]

That makes sense Andrew.. I've been using epoxies for years but don't really understand the intricacies of the stuff... I just do things because that's what someone else before me did, you know ???

[asianflava]

I read in the West systems literature that you can heat (heat gun or lamp) the wood to be covered prior to applying the epoxy. I think it also said to use some kind of alchohol to thin it. I don't have it handy so I can't check.

Edit: I found the info online, it says MEK, acetone, or toluene. Here is the section.

Thinning Epoxy

There are epoxy-based products specifically designed to penetrate and reinforce rotted wood. These products, basically an epoxy thinned with solvents, do a good job of penetrating wood. But the solvents compromise the strength and moisture barrier properties of the epoxy. WEST SYSTEM epoxy can be thinned with solvents for greater penetration, but not without the same compromises in strength and moisture resistance. Acetone, toluene or MEK have been used to thin WEST SYSTEM epoxy and duplicate these penetrating epoxies with about the same effectiveness. If you chose to thin the epoxy, keep in mind that the strength and moisture protection of the epoxy are lost in proportion to the amount of solvent added.

There is a better solution to get good penetration without losing strength or moisture resistance. We recommend moderate heating of the repair area and the epoxy with a heat gun or heat lamp. The epoxy will have a lower viscosity and penetrate more deeply when it is warmed and contacts the warmed wood cavities and pores. Although the working life of the epoxy will be considerable shortened, slower hardeners (206, 207, 209) will have a longer working life and should penetrate more than 205 Hardener before they begin to gel. When the epoxy cures it will retain all of its strength and effectiveness as a moisture barrier, which we feel more than offsets any advantages gained by adding solvents to the epoxy.

[Arne]

a/f, that sounds like a really good alternative. Open the pores and let some real slow setting epoxy get sucked in...... I'll keep that one in mind.

[SteveH]

When building radio control airplanes we thin epoxy all the time for use as a protective "paint" to keep the fuel from soaking the wood. It works great in that application. We even thin it so much we can just pour it into the inside and let soak in as we turn the fuselage to all angles to spread it evenly.

[critter]

hey guys,
found another way to solw the curing process,i did mine yesterday when the shop was cold,it too a long tome to cure,like 10hrs it was about 50 degress,i figured it soaked long enough and will put on another coat today,posted pics in gallery.

[Arne]

Yes, it will cure more slowly, but it also seeps and absorbs less slowly. Wood is cold (pores closed) and resin thicker.... not sure what end result is.

[asianflava]

On the opposite end, if you heat it, it will thin out then setup super fast.

[Arne]

That's why you use a slow hardener, so it won't set up fast. I agree it will set up faster than when cold.

[doug hodder]

If you choose to use a slow hardener in cool temps...you can also run the risk of getting an amine blush....caused by moisture....it'll come off the epoxy, just needs to be scuffed off...and you can also run the risk of more crap getting into the epoxy...I've wet out 16 foot sides on a wood boat with cloth on bare wood just by following the regular recipe given by west systems and gotten good penetration and finish with it, in one shot by myself....I would recommend playing around with it on scrap material if you want to do something different...the directions give the best results...just don't blame the glue system if you doctor it up and it doesn't work like you want....Just my opinion....Doug

[madjack]

If you choose to use a slow hardener in cool temps...you can also run the risk of getting an amine blush....caused by moisture....it'll come off the epoxy, just needs to be scuffed off...and you can also run the risk of more crap getting into the epoxy...I've wet out 16 foot sides on a wood boat with cloth on bare wood just by following the regular recipe given by west systems and gotten good penetration and finish with it, in one shot by myself....I would recommend playing around with it on scrap material if you want to do something different...the directions give the best results...just don't blame the glue system if you doctor it up and it doesn't work like you want....Just my opinion....Doug

when all else fails...just follow the directions .........................................

[DestinDave]

when all else fails...just follow the directions .........................................

Awwww, man - that's too easy. Besides my wife will gladly tell you, that's the first thing I throw away from any new product...

[Arne]

I've noticed that, as well.. I'll put things together, then read the instructions to see if I missed anything.