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I glued my back together using hide glue, and I thought it was a very tight join - very sharp planes, no light with candling etc.

After finishing (no pore filling - Pau Ferro) with KTM 9, and sanding and buffing, the back seam is starting to show. (a very fine indentation along the seam) Is this a function of the finish that I've used? Some reaction with the hide glue? I'd really be surprised if it's a poor join - I've improved my technique over the last 8 guitars - thought I had that licked. Thanks.

Are you buffing on a wheel .. sometimes the heat generated from buffing will cause finish to sink .. into things like seams and pores ... a light wet sand, then polish by hand might do it.

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Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

Corky;
Did you use any sealer?
How many coats of finish?
How long did you let it cure before sanding & buffing?

It still could be a slight gap in the joint.
fill it with more finish and let it dry for a few weeks before
leveling!
Mikey

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Mike Collins

What kind of glue did you use for your back joint. If you used Titebond, its very likely that that is your problem. Titebond is relatively soft. Try LMI's white glue, which is harder and less prone to movement.

I inlay my back strips vs. sandwiching them in and use epoxy in order to avoid this very thing.

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Jim Watts
http://jameswattsguitars.com

Corky:
I have noticed the same thing, however I feel its protruding rather than sinking. I surmised that the hide glue is swelling from the moisture (water) in the KTM9. I have not found a cure for the problem yet, but the good thing is that it will lay down in a week or two. After level sanding and buffing it will disappear unless your gap is not as tight as it should be. Have courage, stay the course........

Mikey

P.S. After re-reading your post maybe you level sanded before it shrank back and now it shrank back to a lower level?

_________________
The Biggest Little City, Nevada
www.hammondguitars.com
I love building guitars!

I had this also with guitars I finished with KTM-9. One year I went to the guitar show in Montreal and specifically sought out guitars finished with KTM-9 and checked some seams. Same thing. So I wouldn't blame myself if I were you.....

Pat

_________________
There are three kinds of people:

Those that make things happen,
those that watch things happen,
and those that wondered what happened.

Sorry Corky for the hijack but inquiring minds...

Pat,
Any similarity on the type of adhesive used in your survey or do you think this is a KTM-9 thing across the board and it needs more time to set up before levelling?

Anyone having similar issues with other waterbased finishes? EM6000?

Mike -
I filled the grain with Zpoxy (even though it didn't really need it - Pau Ferro)
Coats of finish....quite a few (over a dozen) although my crappy HVLP spray gun lays it on pretty unevenly
Time of cure....aha - yeah that may be the issue. I was in a hurry - only a couple of weeks. But even so, if it was
Others asked what glue - hot hide glue for the back seam (with no center strip)

Thanks - Corky

Corky;
I do not like the "dipped in plastic" look .
I want my guitars to have some small pores showing.
Looks like real wood to me that way !
BUT- I find I can not rush a finish.
After final sanding(you can dampen the wood)then sand with 220
again.
This will get rid of most if not all raised grain.
I spray a coat of shellac.
then fill with waterbase sealer.
This can be sprayed on our wiped on.
Spraying is the way to go -it is much more level & has a more consistant thickness .
use 2 to 4 coats.
Let cure for a week and then sand with 320 and do your final coats.
Let cure for a week (more if you use a retarder).
The wet sand & buff.

have you figured what your going to build with that nice set of BRAZZIILLION??

Mike

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Mike Collins

Thanks, Mike,

I didn't see your response until now - useful to do a review or "search my posts" - need to remember that.

I've never used sealer - have always used pore filler (zpoxy these days) then sometimes a coat of shellac. I'll have to give that a try. I'll follow your process.

As for the set of Brazilian, I don't know yet. I've got a couple of sets that I've been holding onto until I think I'm ready for them. I think I've got at least a half dozen more guitars to build before I want to take that on. In the meantime, I've got some really nice Amazon Rosewood that is almost indistinguishable from the Brazilian I have. I'll keep using that.

Have a great holiday!