andrewsrea wrote: ↑Mon Apr 26, 2021 12:12 pm
About 8" off of the work, gives about a 4" to 6" spread. The pattern is fixed and the volume is great and reacts to how hard you press, as long as you follow some rules for aerosol propellant, related to your sputtering:
1.) Plan each coat. Think through it and do a dry run.
2.) Related, always keep your mind on the work and in the moment. This concept is like watching the head of a nail and not the hammer when hammering (or watching the ball hit the bat in baseball). The second you get distracted is when runs, sags etc. happen (IMHO).
3.) Clean your sprayer after each use. Clear the siphon by holding the can or Preval (remove the container first) upside down and press the button. Soak the spray head in thinner. Wipe the sprayer face and inspect to ensure the hole is clear. Clogs are #1 cause of sputters.
4.) Thin the paint according to your plan and work from at least (2) jars or (2) aerosol cans. Visually number them. In my experience, low aerosol pressure and thick paint are the #2 & #3 causes, respectively. Aerosol pressure reduces immediately and exponentially, due to freezing from rapid expansion. I normally only do one thick build coat of finish and do a lot of layers.
5.) If your ambient temp is <70 degrees, warm the paint by soaking the can or preval jar in warm water. Do not do this if the temp is >70b degrees, as I have found this to create more problems (blushing, sputters, sags, etc.).
6.) Start your spray on a test area, for a couple of seconds before hitting your work. Check out the test area and the spray head for sputtering.
7.) Start a few inches off the work and move evenly across the work, shooting for 20 second intervals (enough to do one coat on the face of a Jazz Bass body). Wipe the sprayer and place that can / Preval to the side and use the #2 unit for the next 20 seconds. For lacquer, you can work in layers (intervals) for 10 minutes, before worrying about sags or orange peel (depending on how heavy the coat). Go back to unit #1 when it is warmer to the touch and stop at the first sign (might be sound) of sputtering (off the work, as the action of stopping can cause the worst sputtering).
8.) Don't ever try and fix a sag while you are shooting. Stop as soon as you notice it. For lacquer, it may tighten up as it cures. Then again, you may have to sand it out.
9.) Small 'spits' in lacquer can be hit with a wash coat (mostly thinner and a drop of retarder). Otherwise, I use the razorblade and transparent tape trick to scrape the sputter or drip level with the finish.
Much of that is the same procedure I follow when spraying poly. Except I don't have to think about time. Then again, it probably takes me less than 30 seconds to spray the whole body. In terms of temperature, I only worry about if it's too cold. I've sprayed in the summer when it was above 70° and never had any problems. But I hang it inside to dry. It's not an air-conditioned room, but it's cooler than outside. If I lived in New England or the south, I would be worried about humidity, though. I've had problems with haze, or fogging with poly in humid climates.
As far as fixing a sag goes, I don't know any way of fixing it while you're spraying. I've
tried to feather it out, but you're still spraying more material, which could make it worse. At best, I've always ended up with a bump that needs to be sanded level anyway, so if I see a sag or a run, I just leave it alone until I can sand it flush. I've also used the razor blade and tape method for scraping off imperfections several times.
andrewsrea wrote: ↑Mon Apr 26, 2021 12:12 pm
This is why I love Nitro-lacquer. It is very forgiving. Other than the environmental and safety issues, the only con is it can take a month or more to be ready for trouble-free sanding and buffing.
Every time I do a finish I think: "you know, you wouldn't have to worry about/deal with this stuff if you were using nitro..." Maybe some day. I would have a hard time waiting a month for it cure too, though. I sometimes find it hard to wait three days with poly. Especially if there's something I need to fix.
andrewsrea wrote: ↑Mon Apr 26, 2021 12:12 pm
Jack Higginbotham and Paul Reed Smith both told me their preference for urethane was durability over time and much quicker application and curing. To which new variants can be 95% cured in minutes with UV devices. When discussing the knobs on my 1992 CE24 cracking, Paul said that is the con to urethane - how much hardener to mix in. He said my experience was a period that they put too much hardener in the recipe.
That's pretty much everybody's reason for going with poly... Harder and cures faster.
Rickenbacker switched to a UV cure finish back in 2007. Before that, they were using conversion varnish. I don't know anything about that stuff except that it involves some kind of catalyst. I'm kind of surprised that Gibson is still using nitro on all production guitars. You would think they would have switched to poly back in the '70s, when they were owned by Norlin. I mean, they were cutting corners everywhere else... Maybe they didn't want to do it because Fender
did. I wonder how much they pay in EPA fines every year? I hear they pay them in advance.
andrewsrea wrote: ↑Mon Apr 26, 2021 12:12 pm I use (2) of the Stew Mac 5.5" Foam Buffing Pads on a Dewalt cordless 2-speed drill on a slow speed. One for each grade of compound. I start with them clean and damp and let the compound build while I am buffing. I clean after each use. I typically don't do edges / sides / inside horns with a buffer and hand buff these. Edges have much less paint and are easy to accidentally buff through. Here is the link:
https://www.stewmac.com/luthier-tools-a ... -pads.html
That looks cool. Looks more manageable than the other attachments I've seen. I think I'd be comfortable using that.
andrewsrea wrote: ↑Mon Apr 26, 2021 12:12 pmUnrelated to your questions, that Pepto-pink guitar is awesome and your satin over the Sun King color is better than the gloss, IMHO.
Excuse me... but it's
fuchsia. I mean, really... Pepto pink? So gouache.
Seriously though, thanks. That was my first painted guitar, before I started doing dye finishes, and it was my pride and joy for a little while.
And it
does look like Pepto Bismol in that photo under the fluorescent lights at work. Here are some shots out in the daylight:
This was before I started working with dye, and I thought painting a guitar would be easy. I
busted my ass on this project! I actually painted and finished it
twice. The first time, I used spar urethane because I loved the paint color and I was worried that it was going to fade, and I had read that spar has the highest UV protection. What I
didn't read was that spar urethane gets much yellower that polyurethane, and by the time I was done, the color had shifted considerably. It was no longer the vibrant pinkish-purple, but a weird, muted red. So I had to sand it all off and start over again.
The second time, it came out about as close to perfect as any guitar I'd ever seen. It looked like candy... I was pretty proud of myself... I said I wanted to send it Fender as a resume, with a note on it that read: "I did this with rattle-cans!"
Unfortunately, the weird paint that I used was completely incompatible with polyurethane. After a few months, the poly started buckling and peeling off the body in large sheafs. I just decided to lean into it, and started peeling in strategic locations, and did a little light relicing around the body and on the pickguard. This is what it look like now:
FS54.JPG
FS55.JPG
Though it's peeled more since then. It's a self-destructing work in progress.
You do not have the required permissions to view the files attached to this post.
