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Hi Everyone,

I finished this guitar about a year ago (my 8th acoustic). OO Mahogany and spruce. System 3 epoxy pore fill, French polish Royal Lac finish. It looked fantastic when it was done.

A couple months later I noticed 2 or 3 small (dime sized) hazy areas near the binding edge, but didn't think much of it.

A few other guitars got my attention the past months so this one hasn't been played. It's been hanging in my temp and humidity controlled home.

Yesterday I pulled it down to play it and was shocked at the condition of the finish. There were LOTS of hazy spots and areas. I initially thought they might be areas where the shellac has lifted or separated from the epoxy pore fill layer but the surface of these areas feels rougher.

Here are some pics.







My first step was to go at it with a French polish tampon of alcohol and a tiny bit of pumice. This seemed to fix the lightest areas. The most prominent areas got a bit better but didn't disappear. Eventually I got much more aggressive and hit those areas with 800grit sandpaper wet sanding with olive oil. This got rid of the rest of the areas.

Now I'll do a French polish repair with regular shellac.

Has anyone seen this before? Anyone have any ideas what happened?
I'll give the owner of Royal Lac a call tomorrow to ask his opinion.

I'm still a newbie to all of this so I'm guessing it's a problem with me, not Royal Lac, but I'm baffled.

Thanks much.

First guess would be improperly cured epoxy. Seems from your photos that the problem is most aparent in pores and other filled areas, such as along the binding in your last photo. Often takes months to appear. Possible causes are old epoxy, not fully mixed, cured under low temperature.

Pat

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formerly known around here as burbank
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http://www.patfosterguitars.com

could be trapped moisture .
What was the humidity when you applied the finish?

Mike

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Mike Collins

Did you seal the epoxy pore fill? I am not sure that it's necessary to do so. I seal with either Shellac or seal-lac.

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http://www.Harvestmoonguitars.com

Thanks for the feedback. All useful information.

The temp is constant in the basement workspace although the humidity can vary quite a bit. I'll check my notes to see the dates I did the pore fill and started the royal Lac. That will give me a sense of the humidity at the time.

I didn't use a sealer.

The humidity is controlled in your home but not in the shop? If you're unsure if what the humidity was when you did the finish, I'd say that's the best place to start. I've never experienced french polishing in high humidity, but have witnessed lacquer fogging up in that environment.

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Pat

Did you use any type of oil?

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Stay with the happy people.
--Reynolds Large

Moisture will whiten shellac. Similar situation to rings on antique tables from sweaty drinks glasses. My first try would be to gently warm up those areas with a hair dryer or heat gun. Haven't done this on a guitar, but I have had pretty good success on furniture restoration.

I too am guessing an epoxy pore fill. It looks like amine blush to me. I've had this happen too and is one of the reason I won't use epoxy for filling anymore.

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Jim Watts
http://jameswattsguitars.com

I went back in my notes and it must be the humidity when I did the finish.

Once I read my notes I realized I used Stew Mac water based pore fill, not epoxy so I can't blame epoxy pore fill.

I did the finish in the height of the summer and the humidity can be quite high. I thought I could get away with it. At the time it looked like I had. I've experienced lacquer blushing from high humidity.

In the last year I've gotten tighter control on the humidity in my basement workshop. Hopefully I won't see this happen again.

Thanks everyone.

I have had some problems with water based pore fillers under shellac. Never understood whether it was because I didn't sand back properly or what.

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Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

Looks like the epoxy fill maybe delaminating from the wood to me.

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Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/

I've never seen this happen but I'd guess it was because of using alcohol and french polish on the epoxy before it was fully cured. Cure times for the epoxy can vary widely, pretty much as Pat Foster said.

No Epoxy? Cancel the above

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Joe Beaver
Maker of Sawdust

So there is no epoxy under the shellac, water-base pore fill?
It still could be the pore fill, if you didn't sand it off the surface well enough.

I've never seen that white look on any of my "Kusmi shellac only" finishes, not that they don't look ratty otherwise...

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