Filler or putty for under epoxy?

Jeff Reardon

Jeff Reardon

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By next weekend I hope to be done stripping glass and on to sanding and prep for re-glassing.

I have some gouges from the glass stripping, mostly in places where staple left in the glass pull small strips of wood with them. I'd like to fill these, as well as some other imperfections in the hull, prior to the initial coat of epoxy.

I know I could fill with epoxy mixed with wood flour or some other filler, but am wondering whether I can use a commercial wood putty. Anybody got a favorite product?
 
I think the no sag low viscosity epoxy with micro balloons would be a better choice than a typical wood filler due to the bonding capability of the epoxy in the low spots and holes. I think I would "slather" on a layer over the entire hull and then sand to fair.
 
I'd use epoxy & micro balloons. Better bonding both to wood below & glass epoxy mix above. The micro balloons are a LOT easier to sand than the wood flower mix. I'd use a batton stick & mark all low spots, fill then sand fair. If the wood is dry, I'd paint unthickened epoxy in low spot, wait a couple of min. then fill with the thickened mix. If ya don't have a bunch of spots to fill, I'd fill one at a time. To put a layer over the entire hull then sand down is more sanding than I'd want to do. IMHO Good luck
Dennis
 
I used the same epoxy for wetting out the cloth (West Systems) thickened with wood flour. I also used Cabosil as a thickener, but that is harder to sand. The woodflour worked good, simply used saw dust from a band saw, and ran it through a flour sifter to get the big chunks out. Dave
 
Everyone seems to be singing essentially the same tune. Assuming I use epoxy and filler, should this be applied before the intial coat of epoxy on the entire hull, or after?

I'm thinking I want to apply the putty/filler into any major flaws in the hull, small gaps between strips, etc, then sand the entire hull, then apply a coat of epoxy over everything prior to glassing.
 
Jeff, you need to apply the wet epoxy first, as was described above. You need to bond/seal the wood first with un-thickened epoxy. I mix up the epoxy, then paint it on the bare wood, then add my woodflour to the mix. I used a body filler spreader to spread and fair the thickened epoxy.
You definitely need to seal the wood with the un-thickened first.

Dave
 
Thanks. Is there any reason to coat the entire hull, or can I just put down unthickened epoxy, then follow with thickened epoxy, in the areas to be patched?

By the way, this forum is amazing as a source of information for this stuff. I'd be (even more) lost without it. Thanks again, to everyone.
 
Jeff, I would not coat the entire hull. If you coated the entire hull, then you need to sand it again when you go to lay the glass to create a tooth for the epoxy. Just paint the areas you will fill, as they will be sanded before you lay your cloth. Dave
 
Excellent. A good excuse to speed up my epoxy order!

Got a new spot for materials storage in the man cave all cleared out over the weekend.
 
Jeff, I would not coat the entire hull. If you coated the entire hull, then you need to sand it again when you go to lay the glass to create a tooth for the epoxy. Just paint the areas you will fill, as they will be sanded before you lay your cloth. Dave
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I agree. I think you will get the best adhesion for the first coat epoxy, on bare wood. You want the glass in that first coat. I would just fill the gaps and holes that will effect the cloth laying properly. You will need to fair again after the cloth is layed out anyway, if you want to fair at all.
 
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