Official Luthiers Forum!

What is the diluting solvent?

What ratio?

What do you apply it with?

Does it dry streak free, or do you need to level it after as well?

What else do I need to know?

TIA

If you are asking about a washcoat as a final step when doing pore filling, I've diluted the epoxy 1:1 with denatured alcohol. I've done it that way for Z-poxy and System Three SilverTip.

I've wiped it on with a paper towel (wearing gloves). Has to be a lint-free paper towel.

I haven't seen any streaking with drying and it goes on so thin that there's nothing to level.

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Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

Yes, those are exactly the answers I’m asking for, thanks!

I'm more this dilution(*) https://www.youtube.com/watch?v=wvS98dojNVs&t=4s
ITime - 0.44
But I use alcohol, isopropyl.
Can be slightly streaky, but that disappears with a scuff with green Scotchbrite pad.
* - maybe 1-10, 5/6 coats

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

The way that goes on looks very nice and easy! I notice in the comments on that video that he has since switched to a coat of shellac…

I’m also not sure what the * numbers present…

Sorry for the obscurity, dilution around 1 epoxy to 10 alcohol and I use around 5-6 coats.

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

https://www.westsystem.com.au/wp-conten ... _epoxy.pdf

I know not every one uses West System, but I think much of the information applies to epoxies in general. The part about shrinkage might be concerning to some people. Excessive thinning can also make epoxy cure softer. A thin coat on the surface may never cause problems, I don't know. Finishing fails often take time to show up.
I thin epoxy about 5% or less when doing pore filling but try not to exceed that percentage, but then I am mostly using it to even out the bleed through from laminating.

After watching Ken Parker’s epoxy finish video,
I bought some of the Kimberly paper towels and apply Zpoxy full strength, wiping off excess.

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wah
Wah-wah-wah-wah
Wah

I have several guitars in the wild for years now using well thinned wash coats under EV (one). I see quite a few of them now and again and have had no problems reported or seen..

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

It’s OK Colin, you’re Scottish. I’m not meant to understand what you say the first time through…;)

interesting read! I will try very hard not to sand through the last coat and use thinner as a last resort…

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

I'm just impressed that Colin used a baseball metaphor in a different thread (i.e., hitting it out of the park). I mean, I know you have baseball, but you have it the way we have curling.

Tech support System Three recommended lacquer thinner for thinning Silver Tip.

Fwiw, I burned through. Used a 50/50 wash coat and you can’t see it through the seal Lac. So far…

Ed, if you can spare the time, what is the finish you want to achieve? Thanks!

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Peter Havriluk

This is prep for a couple of PC Royal Lac axes.

What I would like to achieve is a 1.5 mil coat like this guy I know. What I will achieve remains a mystery…

I am pretty much old school with finishing, meaning that I don't like to mix different types of finish. I know a lot of people here have lots of experience at pore filling with epoxy and other finishes over (i.e. Shellac, lacquer, oil). However I personally stick with one finish all the way through.

The question I have is has anyone tried this method of using epoxy as the final finish? It seems it would be quite durable and thin if put on as multiple wash coats.

I am going to give it a try on some scrap but if anyone has tried it I would appreciate feedback on how it works.

Thanks,
Bob

I was wondering the same…

If I were to use epoxy as a top coat I would not thin it. Most thinning agents cause the epoxy to cure softer. Warming the epoxy might be a better way to lower the viscosity to help it flow better. Also considering that epoxy doesn't "burn in" like nitro, after pore filling, a single moderately heavy coat that is thick enough to sand and buff out might be a better way to go.
When an epoxy coating is used on the bright work of boats it is usually followed with a top coat of varnish with UV inhibitors added - epoxy doesn't like sun light.

Thanks for the info Clay,

I thought it may have been a viable option, but if thin coats show witness lines it wouldn't be much use as a FP type finish.

My go to finish is nitro, but have done the last 2 French Polishing with shellac and have had very good results. Thought about Royal Lac but have read too many "issues" about it.

Too bad, I was getting excited about the idea. I may still do some experiments on scrap to see what I can do with it.

Thanks,
Bob

A bit off topic, but what issues concern you about royal lack? I have FPed 4 guitars with it now and any issues separate from regular shellac were minor. True, you lose the burn in repair aspect after 30 days or so, but I have had to pause French polish for more than 30 days and found the royal lack continued to build on cured royal lack with no noticeable visual problems.

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Bryan Bear PMoMC

Take care of your feet, and your feet will take care of you.

Personally, I’ve always used Z-Poxy pore fill, I’ve always applied a final coat thinned 50% with denatured alcohol, and I’ve never had any problems with either adhesion or witness lines. Some of these guitars have lived in my home for 10+ years.

The purpose of the final thin coat is simply to even out color from any sand through. Some prefer to sand back to bare wood. I prefer the wash coat because of the incredible way it pops the grain.


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I think the problems with Royal Lac are basically in the past. Lots of people are using it with great success.

As for washcoats…I did one successfully on a ziricote guitar, but I got the mix ratio a bit wrong on a splated bubinga guitar in the works, so I elected to sand back to wood on that one. We’ll see how many pores show once done.

Hi Rob,
Although I would suggest applying one coat that is heavy enough to sand and buff, epoxy can be recoated without sanding if the next coat is applied before the first is fully cured. Whether it will show witness lines when done this way I don't know. It would certainly be worth testing if you are inclined to use epoxy as a top coat.
Here is some information about using epoxy as a barrier coat (again, directed at the boat trade):
https://www.westsystem.com/instruction- ... r-coating/