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I have been buffing out my EM6000 finish and noticed this on the headstock. I couldn't seem to buff it off, so I went back and re-sanded it, then buffed and there it is again... What on earth is it and why can't I get rid of it? Any thoughts or suggestions?
Thanks,
Steve

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Steve Sollod (pronounced sorta like "Solid")
www.swiftcreekguitars.com

Witness lines?

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Wisdom is justified by her children

Yup.
Water based finishes don't melt in with each coat.
Sorry.

EM6000 'should' burn in, shouldn't it?

Epoxy pore fill? Looks like you're through the finish and into your fill...

I don't see how it could,
being water based.

EM6000 has full burn in to previous coats, even many months later.
I agree it looks like witness lines to some undercoat....... I've only used EM over shellac & have never seen this. (Can you list your schedule?)
Maybe too aggressive dry sanding too early? (...I know you asked about grits & wet-sanding earlier)

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Dave
Milton, ON

Looks like witness lines to me also.
Tom

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A person who has never made a mistake has never made anything!!!

I am in the middle of finishing one with EM6000. I’m actually at the point of waiting the month for it to cure.

I had something similar on the back when I was leveling between coats. I continued to sand and the spot got bigger. I am thinking it was a sand through to my zpoxy layer. I had this in a few spots. Come to think about it, I had it quite a bit until I stopped sanding and concentrated on just getting coats on there. I re-sprayed and it went away. I’m not seeing anything that looks like witness lines after the re-spray.

My big hope is I don’t end up with any sand through like you are dealing with when I get to the buffing stage. I’m curious about what your buffing process is (just cause I’m trying to decide how I’m doing it).

One thing I did learn is the importance of getting the zpoxy layer level.

EM 6000 WILL melt with each coat. But, I'll bet you sanded to a high grit the applied new finish. Or waited a long time between some coats. But I'm going with my first idea. Regardless, reactivate surface with DNA before spraying new coats if you sand high. I've seen this before. Witness lines.

Only solution now is to sand through it all and add new finish to rough surface, activated with DNA.

Mike

Water based finishes will not melt.
Period.

They won't.

EM6000 is not water based; it is waterborne. There is a difference. It does contain solvents. According to the manufacturer, and a lot of luthiers who use the stuff, it does have 100% burn in.

http://www.targetcoatings.com/products/ ... cquer.html

What Charlie said. Think of EM as a "mayonnaise" of solvent based droplets of finish suspended in water.

I'm just finishing one and saw this as well though after wiping a sag. The instrument looks fine after another 10 or so coats but we'll see what happens when I level and buff next week. BTW first time using EM6000, used USL for my prior WB finishes.

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EM6000 absolutely will melt into new coats. I am not attempting to contradict anybody on their experiences with other finishes. However, there is a resistance to proper melting if the substrate is already highly sanded/polished or it has cured for a long time. You must rough up the surface and/or activate with DNA. None of this applies to concurrent application of build coats. They melt quite easily. The only issue here is orange peel. And this must be dealt with early on by sanding flat after 8 coats or so then getting back to the schedule.

Mike

I use KTM 9 and it cross links just fine. I don't get witness lines, none. Maybe with KTM 4 but not with KTM 9.

From what I see you have a classic case of the dreaded sand through. As long as the undercoat wasn't sanded through also it should be easy enough to fix.

Good luck

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Joe Beaver
Maker of Sawdust

This is not a huge problem because of where it is. The Peghead face should be sanded until the issue disappears. It's a small area.

Mike

For what it's worth, I have seen witness lines disappear during buffing. The only danger is getting the lacquer too hot from buffing and getting a burn through.

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I don't think you can 'sand until it disappears'...
You can see how the edge near the nut is duller than the rest, which is what made and still makes me think you're through your finish and into your pore fill. Did you use epoxy? Please tell us. I think more sanding is going to cause you more problems.
Scuff the peg head lightly to 240, and respray your normal number of topcoats...

I'm not so sure. The more I look at it, the more it looks like a spraying of lacquer over a sand through of the base coat (ie epoxy I'm guessing), without fixing the sand through first.
Guys who use epoxy pore fill, particularly who sand aggressively back close to bare wood, advocate a final thinned coat of epoxy to seal sand throughs / unify colour.
Worst case, you could sand everything off the face (to bare wood), seal normally, brush (or airbrush) EM6000, cure & then level/buff. Bummer if you're as impatient as me, but maybe the only reliable fix.

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Dave
Milton, ON

It looks like a sand through to me. I don't use waterbornes, but I'd recommend following Medd's advice.

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I've gone back and sanded again, followed by buffing. It appears to be witness lines... What do you think? I didn't think this was a problem with EM6000. I don't think I sanded through to the z-poxy. Could it have been caused by conditions in my shop, (closed garage with window air conditioner) such as humidity? The rest of the guitar came out fine. This was my first attempt at spraying and with EM6000. I was very pleased with the product and my technique. But I'm puzzled by this... I'm tempted to go ahead and assemble the guitar (This is not a commission) and come back to it sometime in the future. I don't think I can bear to wait another 4-6 weeks... (BTW, This is number 7.)

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Steve Sollod (pronounced sorta like "Solid")
www.swiftcreekguitars.com

It isn't

Well, as I say, I think you might have (I also see a heart shaped something SW of the "e" hole in the last shot. Do a test.... z-poxy some scrap, sand through in a couple of spots, brush on some EM6000 & have a look.

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Dave
Milton, ON

Okay,
I give!

It's the headstock. It's not really a high wear area of the guitar, but it's a place that gets looked at. I'd recommend French Polishing over the top of what you have. I suspect it would look good afterwards.

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I didn't mean to say it, but I meant what I said.
http://www.brackettinstruments.com/