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PostPosted: Sat Feb 24, 2018 11:23 pm 
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Cocobolo
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First name: Phil
Last Name: Hartline
City: Warrior
State: Alabama
Country: USA
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Never got this guitar completed because of a bad finish. So while recovering from surgery, figured the time was right to give it another shot. Problem is, this is the worst finish in the world. Took forever (many months) to cure, and remained unstable for two years. After curing, it sat against a plastic garbage bag, which dissolved the finished. I peeled the bag off, it ruined the surface. Then it sat against a nylon gig bag, which also dissolved the finish and I had to peel it off. So, time to strip this one down and apply something else. Problem is, I'm having a terrible time getting this finish off.

My scraper peels shavings like plastic. Sandpaper doesn't make dust, it makes rubber shavings like you get off an eraser. Lacquer thinner and Acetone will both dissolve the finish, but not allow you to wipe it off. Instead, it raises the finish, making a sticky mess that then dries hard, which means more work with the scraper.

OK, so what is this finish? Was my first guitar, I made the mistake of trying local finishes. Started with a coat of shellac, then used some water based grain filler I got from Stew Mac. After that I tried the off the shelf stuff. Deft in a brush on, Deft in a spray, then some automotive lacquer I got off the shelf. Thought I took it all the way back down before each type, but who knows. What I ended up with is a soft, but checked, finish that is very glossy until it touches something and dissolves. It will not scrape or sand off, and even paint stripper just turns it into a sticky rubber like glue that you can't scrape off.

So, maybe I am not using the chemical stripper right, but I am at a loss here. I figure it ended up with a combination of chemicals, lacquer based but with lots of plasticizers. Any ideas on how to strip this thing down? Too pretty an instrument to not finish.

Thanks, kind of at a loss here.


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PostPosted: Sat Feb 24, 2018 11:37 pm 
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I would try Citristrip. It is less toxic than most strippers, and it seems to do well on a variety of finishes. Typically dries after application and peels off like dead skin after a bad sunburn. May take 2 or so applications if the finish is thick. Just paint on a thick coat of the Citristrip, let it dry, and scrape it off. Good luck.


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PostPosted: Sun Feb 25, 2018 12:07 am 
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Brazilian Rosewood
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This stuff will probably work:
www.homedepot.com/p/Rust-Oleum-Automoti ... /204643900

The safety data sheet says it contains less than 85% methylene chloride, 15% methanol, 5% hydrotreated light distillate. It has so many nasties in it , it should strip anything.
When I buy stripper I look for the one that has the most methylene chloride. It is very effective as a stripper and also very toxic, so use it in a well ventilated area (outdoors) protect your eyes and skin, try not to breath the fumes and don't heat it or it may give off phosgene
gas (you know- the chemical warfare agent). But it will generally strip just about anything. In high enough concentrations I have even stripped polyester finishes with it.


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PostPosted: Sun Feb 25, 2018 5:46 am 
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You will need a methylene chloride-based stripper intended for epoxy and other difficult-to-strip finishes. We use three strippers in the shop:

- Citrus-based strippers for lacquer-only finishes or where there are plastics that we wish to preserve

- Moderate-content methylene chloride strippers for one-part urethanes, traditional varnishes, and combination finishes (e.g., wiping varnish over latex fillers)

- High-content methylene chloride stripper labeled for epoxy, two pack urethanes and polyesters, and - in general - anything that annoys us

Orange strippers eventually get most jobs done, assuming there is time and energy available for the job. The biggest issue with them is that they are slow, and will not lift the finish layers in a uniform fashion, making 'apply-wait-scrape-reapply-wait-scrape' the rule. I like these strippers for simple jobs like stripping an all-lacquer finish, but they eat up time and energy on anything else, and are largely ineffective on the vast majority of modern finishes - especially thicker polyester filler base coats topped with poly color or clear coats. In terms of the cost, orange-based strippers are the most expensive strippers we use due to the multiple application cycles needed, but the cost is justified where we are able to preserve delicate plastics that test as safe to strip (many are not safe to strip with any stripper!).

We seldom use moderate-content methylene chloride-based strippers for the simple reason that paying almost as much as high-content methylene chloride strippers, but getting a fraction of the good stuff that actually does the work seems to be financially irresponsible. Higher-content methylene chloride strippers labeled as epoxy strippers puts more active agent on the finish, increases the odds of finish removal occurring in a single application and in a single unitary sheet, and is the least expensive option we've seen when both time and materials are taken into consideration. The downside is that for instruments bound with plastics, mechanical stripping must be used, or another stripper - usually a 'green' or safety stripper - must be tested and - if determined to be safe - used.

For your situation, Jasco Premium Paint & Epoxy Remover or KleenStrip Premium Stripper should remove anything and everything on the surface. The opportunity to get a clean lift of the the finish has already been lost, so it is time to work section by section and do a detailed removal with a higher-strength product.

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PostPosted: Sun Feb 25, 2018 9:07 am 
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Brazilian Rosewood
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I've used the kleenstrip premium stripper, and it works well, their regular stripper is not as effective. The premium contains over 50% methylene chloride.
At one time, years ago I worked in a cabinet shop that also refinished furniture. They would buy stripper by the 55 gallon drum. The "active ingredient" was methylene chloride and I think the rest was whatever toxic waste they could dispose of by adding it to the mix. gaah


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PostPosted: Sun Feb 25, 2018 9:34 am 
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Brazilian Rosewood
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Just another reminder why I am no longer doing refinish work......

I used basically the same as Woodie mentions when I did. One question what are your bindings? If they are anything but wood be ready to replace them as anything that will eat the mess you have stacked on there will eat them.

Since you mention cut rate home depot lacquers my first step in those cases was to wick off as much lacquer as possible. Cover the surface with two layers of paer towels and soak with acetone. Keep the towels wet with acetone but not running off the surface, it evaps quick. After some time you will see the paper towels turn yellowish. That is the lacquer wicking up. Use the paper towels to wipe the surface followed by a clean towel soaked in acetone and what ever gelled will wipe up. You may need to repeat this 3-4 times but at that point you should be down to your first closed polymer resin. At which point convetional sanding may be all that is needed.

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PostPosted: Sun Feb 25, 2018 9:41 am 
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Cocobolo
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Thanks for the suggestions. This is what I used, Zip Strip Premium. Looked this morning, it does contain the nasty stuff, but doesn't say what concentration. Also included a pic of how thick i put the stuff on. Need thicker maybe? OR multiple applications?

I can try the paper towel trick and see how it goes. I did soak a paper towel with acetone before buying the stripper, it dissolved the finish and then stuck to the surface. May try soaking it as you said, see if that helps.

My bindings are wood, so no concerns with that. Hope to get this off without damaging the sound board, for some reason the finish there came out real nice.


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PostPosted: Sun Feb 25, 2018 10:48 am 
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Throw the Deft away. Never, ever use it again.
It does not get hard.

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PostPosted: Sun Feb 25, 2018 4:31 pm 
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Brazilian Rosewood
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Zip strip premium's MSDS lists the percentage of methylene chloride as 71.38. That should be plenty. You can do multiple coats but don't let the stripper dry on the surface.


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PostPosted: Sun Feb 25, 2018 9:31 pm 
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Brazilian Rosewood
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Zip strip premium will work just fine if you do a small area at a time. That way you can remove it before it dries.

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PostPosted: Sat Mar 24, 2018 2:14 pm 
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Walnut
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Thanks for all of the great info here. I’m planning to refinish the cedar top and maybe the entire body of my guitar #1 from 5 yrs ago. Rattle can lacquer, which came out OK, but getting much better results with my current finishing process. I think the citrus stripper should work well for the thin lacquer finish.


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PostPosted: Sun Mar 25, 2018 7:51 am 
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Cocobolo
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It is also a good idea to keep to the same manufacturer for base coat, sealer and final finish and then that way you know they will be compatible.


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