Official Luthiers Forum!

Gotta bite the bullet and do a porefill.

I have three tins leftover from days of yore, a 105, and both a 205 and 206 hardener.

I can't remember what the combo and mix ratio is.

Also, what's the shelf life of epoxy? This stuff is likely at least 5 years old, any chance it's still good?

From what I've read epoxy has an indefinite shelf life. Some epoxies will start to crystalize but can be brought back by warming in a hot water bath.
I believe the mix ratio for 105/205 or 206 is 5 to 1 by volume. The hardener may have darkened so when mixed with 105 may show a slight amber caste.

Thanks

The products should be OK, but don't use the 205 or 206 for pore fill applications. Use the special clear hardener, 207, which is mixed in a 3:1 ratio. The 207 avoids any potential for blushing/blooming problems down the line.

_________________
Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

http://www.goreguitars.com.au

Too late!

My 207 special clear was red and chunky, but the 206 was fine, so I used it. Hopefully it'll be ok...fingers crossed!

Even after the 207 is ruby red it still works fine. Warm it up and see if you can mix the chunks back into the liquid. It's 3:1 by volume and 3.7 : 1 by weight.

I expect that putting a layer with 207 over a layer with 206 might not be wise...

If you sand it back to where the epoxy is just in the pores you might be O.K. What is the wood it is going on?

Walnut.

If you sand back to where the 206 mix is only in the pores the only potential problem I could see would be it eventually turning opaque in the pores (and that might never happen). If you stained the walnut with a dark (walnut) alcohol based dye stain it might sit on top of and be partially absorbed into the epoxy, so even if the pores did turn yellow they would be under a layer of dark stain. It usually takes epoxy about a week to fully cure and alcohol is a weak solvent for it so that is why I would try an alcohol based dye stain.
You might be fine sanding back and just top coating with 105/207 epoxy mix , but a dye stain can sometimes enhance the look of walnut.

When using 207 the mixing ratios are different when mixing by volume vs weight.

Volume 3 : 1
Weight 3.5 : 1

_________________
I'm not a luthier.
I'm just a guy who builds guitars in his basement.
It's better than playing golf.

Thanks folks. I got away with using the 206 for years without issue before I knew that 207 was the way to go. Hopefully I'll get lucky again.

Do you usuallbwait a week to cure before adding finish?

I usually wait a week before finishing because I wait until the epoxy is cured before I sand it.The dust from sanding uncured epoxy can be a sensitizer and eventually cause allergic reactions and make it so you can't work with epoxies. i don't want that to happen to me. One of the advantages of being a hobbyist is I have all the time in the world.