Acoustic Guitar Construction

kencierp wrote:Drying problem --- my first trouble shoot would be -- recoating too soon, each layer has to gas off completely. Heavy coats (brushing lays down about four times the thickness of a drip free spray coat) takes much longer for primary cure (Tony I know you don't call it that) So if the solvent gases get trapped they soften the next layer and so on --- $.02

I assumed that was the issue. This is my typical schedule:
2 coats per day about an hour apart
wait 24 hours
repeat until I have 8-10 coats.
Cure/ dry/ perform alchemy for a week while a fan blows on the box. I scuff the finish each day with 600 or 800 grit.
Begin wet sanding after a 7-10 days or more of cure/dry/alchemy time.
After wet sanding, I let the box sit overnight before buffing
After buffing, I let the box sit overnight before beginning to assemble and set it up

Additional info:
I did not have this issue with the semi-gloss Deft lacquer. I believe the semi-gloss has more solids than the gloss, and therefore less solvent to gas off. I am applying the same thickness of coat and so I might not be giving enough time between coats? Maybe only one coat per day or if I do two, they should be further apart than an hour.
Any thoughts?

TonyinNYC wrote:

kencierp wrote:Drying problem --- my first trouble shoot would be -- recoating too soon, each layer has to gas off completely. Heavy coats (brushing lays down about four times the thickness of a drip free spray coat) takes much longer for primary cure (Tony I know you don't call it that) So if the solvent gases get trapped they soften the next layer and so on --- $.02

I assumed that was the issue. This is my typical schedule:
2 coats per day about an hour apart
wait 24 hours
repeat until I have 8-10 coats.
Cure/ dry/ perform alchemy for a week while a fan blows on the box. I scuff the finish each day with 600 or 800 grit.
Begin wet sanding after a 7-10 days or more of cure/dry/alchemy time.
After wet sanding, I let the box sit overnight before buffing
After buffing, I let the box sit overnight before beginning to assemble and set it up

Additional info:
I did not have this issue with the semi-gloss Deft lacquer. I believe the semi-gloss has more solids than the gloss, and therefore less solvent to gas off. I am applying the same thickness of coat and so I might not be giving enough time between coats? Maybe only one coat per day or if I do two, they should be further apart than an hour.
Any thoughts?

Yup...I think Ken hit the nail on the head...and I think you are correct also Tony with the solids issue...
when we were shooting cars back in the 50's...we had NO drying problems...but products have changed dramatically. I honestly can't remember the solids % of that stuff off the top of my head...been too long ago...
yeah, I haven't used stands with that crap on them in many years...it will EAT a finish...
Not much to do about allergies to lacquer...I used the brushing lacquer for something else the other day thinking I could get away with it now and I looked like I had slept in a patch of Poison Ivy....guess it never goes away....I just have to find a water-based product that will work for me satisfactorily there MUST be something out there...
I was amazed at the finish Kathy achieved with EM6000 on Her recently finished Koa Weissenborn and except for the last 3 coats she BRUSHED it on with a total of 17 coats and from what I can see...no hint of BLUE...

http://home.comcast.net/~kathymatsushit ... iss17.html

I haven't tried Hood products yet and that's where I'm going next, from what Ken says...it's the Cats Me-yow...MINE "Cat Scans" EVERYTHING...so I should know right off! :>)

Thanks all!

Ray

Actually the only "Hood" product I have used on a complete instrument is the lacquer based pore filler, but honestly now that I have varification that Zpoxy is compatible with nitro lacquer that will be my pore filler of choice. I still like Por O Pac but the Z is easier to apply and plus it is clear.

I tried the Hood clear lacquer filler and I wasn't totally pleased. It did not fill everything per their instructions for use. I think for clear I'm going to go with zpoxy too. I used regular Duco type epoxy on 3 guitars that have some finish issues and I don't know for sure, but the epoxy could have a play in there.
Ray, have you tried Tru Oil?

Kevin

Kevininca wrote:I tried the Hood clear lacquer filler and I wasn't totally pleased. It did not fill everything per their instructions for use. I think for clear I'm going to go with zpoxy too. I used regular Duco type epoxy on 3 guitars that have some finish issues and I don't know for sure, but the epoxy could have a play in there.
Ray, have you tried Tru Oil?

Kevin

Yes I have kevin, and that's a real option..no problems there...started out doing necks on electrics for myself and loads of other people...have never tried a whole guitar...but I have seen some great results!

Kevininca wrote:I tried the Hood clear lacquer filler and I wasn't totally pleased. It did not fill everything per their instructions for use. I think for clear I'm going to go with zpoxy too. I used regular Duco type epoxy on 3 guitars that have some finish issues and I don't know for sure, but the epoxy could have a play in there.
Ray, have you tried Tru Oil?

Kevin

Z-Poxy is compatible with nitrocellulose lacquer, per the manufacturer (thanks to Ken Cierp for emailing them to find that out). Other epoxies may not be and that may be where you finishing issues stem from Kevin. Structural epoxy would most likely not be compatible because its purpose is to hold objects together, and not be dissolved by any solvents. Finishing resins, which Z-Poxy is, are designed to be top coated with a finish and therefore, it would stand to reason that they are not resistant to solvent based finishes.
If I remember correctly, from the email Ken received from the manufacturer, nitrocellulose lacquer will burn into Z-Poxy Finishing Resin but not their other epoxy products. Lots of people like West Systems Epoxy for pore filling, but I don't know of anyone who has emailed the company to find out if it is compatible with nitro. I will stick with Z-Poxy because it is fast, pretty easy, and is compatible with my finish of choice. It does not have a strong smell, so I can apply it in my house which is important to me since I am usually pore filling when it is too cold to do it in my unheated, detached garage. I have done it in the garage at 35-40 degrees and the Z-Poxy is even more viscous than normal. Makes it tough to get into the pores.

re cold work area and Z-poxy: I work in the cellar which can get chilly, and a daughter took pity on her poor Dad and bought him a coffee cup warmer from Brookstone, which also works dandy to keep epoxy cups warmed up. And keeps the teacup from cooling off. Looks like a little hotplate, solid flat surface.