black poly touch up

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black poly touch up

Postby Ryan Mazzocco » Wed Mar 06, 2019 2:55 pm

I'm doing a job for a guy, sort of off the books... He got a craigslist Epiphone LP special for quite cheap and brought it in to the store to have it strung up.
Yada yada yada, there was more work that needed done, probably more than it's worth. But I'm doing it for him anyway. Call it building customer relations, but there was some selfish motive as well as I just wanted to take on the challenge.
Long story short: the fretboard was coming off from about the nut to the 3rd fret and some of the wood was splitting out along the fretboard/neck joint as well as finish chipping out.
I pulled the fretboard, reglued it, filled the gaps, scraped flush and now I'm on to repairing the finish.
It's an Epiphone LP Special, so am I correct to assume it's a polyurethane?
I need to blend the black on the neck back in. What's best to use for this? It's too big of an area for the old sharpie, I think I really need to blend it back in and clear coat over it.
Thoughts?

Thanks,
Ryan
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Re: black poly touch up

Postby Glenn Cummings » Thu Mar 07, 2019 11:02 am

Usually the best thing to do when you aren't sure is nothing.
There is nothing wrong with telling him that this is not in your current skill or experience set.

But since you have started it, you pretty much own it for now.
The usual approach is to 'spot test in an inconspicuous space'

Here are some hints.
excerpt: "But applying a finish over an existing finish is one of the riskiest operations you can do in finishing because it can result in any number of problems. These include blistering, wrinkling, fish eye, orange peel and poor bonding.

Problems are difficult to predict, but there are three measures you can take to minimize your risk:

Make sure the surface is clean.
Make sure the surface is dull.
Avoid using a finish that contains a solvent that could attack the existing coating."

Source: https://thefinishingstore.com/blogs/new ... imes-works

The toughest part is that this finish area requires play-ability beyond just looking good.
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Re: black poly touch up

Postby Barry Daniels » Thu Mar 07, 2019 11:21 am

I have had good luck with Glu-Boost products. You can get a kit that has black tint to mix into the CA. Nice thing is it cures quickly so you can start sanding and buffing the next day.

https://gluboost.com

Here is a touchup to a black nitro headstock I recently did. The repaired area is not noticeable. It is a strip a quarter inch wide right behind where the nut sits.
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Re: black poly touch up

Postby Ryan Mazzocco » Thu Mar 07, 2019 7:26 pm

Glenn Cummings wrote:There is nothing wrong with telling him that this is not in your current skill or experience set.

You're absolutely right about that. And we did have that conversation, but he's not worried about it and it's something I would like to add to my skill set, so we are on the same page here. Even if I totally botch the finish repair he'll still have a guitar that he can play, which is more than he had before.

Barry Daniels wrote:I have had good luck with Glu-Boost products. You can get a kit that has black tint to mix into the CA. Nice thing is it cures quickly so you can start sanding and buffing the next day.

Thanks Barry. I was thinking this could be a glu-boost job. I might be giving that a try.
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Re: black poly touch up

Postby Waddy Thomson » Fri Mar 08, 2019 1:09 pm

There is the black Glu Boost tint, and there is also a black gluBoost CA. Not sure off the top of my head if it's Fill n Finish or Thin.
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Re: black poly touch up

Postby David King » Sat Mar 09, 2019 1:29 pm

Most of the other CA manufacturers sell a black, gap filling CA. I'm a little hesitant to pay 2x for the gluboost brand but it's possible that it has some miracle properties that I need to experience for myself to appreciate. I usually end up with Bob Smith's since I can buy it at the corner hobby store every day of the week.
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Re: black poly touch up

Postby Bob Gramann » Sat Mar 09, 2019 1:54 pm

Aside from the accelerator which ought to work with any brand of CA, the only thing that I find makes the Gluboost brand special is the stainless steel pin in the cap. I can screw off the cap and ghe glue will come out of the bottle without me picking at the hole for a few minutes. I’m not a big CA user, ut I’ve actually been able to use more than half of a Gliboost bottle before it yellows and thickens. Not so with the other brands. For me, I’m buying convenience.
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Re: black poly touch up

Postby Barry Daniels » Sat Mar 09, 2019 3:30 pm

Glu-Boost is different. I have only been using it for a month, but it seems to work around finish better than most brands. That repair to the black Gibson headstock shown previously was remarkable. I don't think it shows up in the photo, but it blended in seamlessly and it only took me maybe 5 minutes to level sand it and polish. I was pretty floored.

Mixing in the colors also is nice because the glue will sit there for 30 minutes before curing which gives you plenty of open time.

It is expensive but it has already paid for itself. I am getting ready to really put it to the test. I have some chip outs on the edge of a neck's heel that happened during a difficult neck removal on an old Yamaha. I am going to mix up some dark red-brown CA and try to fill and blend it in. If it works, it will save me from having to do a nitro finish repair. Keeping my fingers crossed.
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Re: black poly touch up

Postby Waddy Thomson » Sun Mar 10, 2019 10:40 am

Glu Boost is the only CA I can use without going into an asthmatic funk for 3 or 4 days. For normal use, i.e., small repairs, gap fills, etc., I don't need a respirator. I have used it for pore filling, and for that I wear one due to the excessive amount of fumes. Also, the accelerator is pretty benign. Nothing that is irritating that I can tell.
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Re: black poly touch up

Postby David King » Sun Mar 10, 2019 2:16 pm

Waddy, that would indicate to me that GluBoost is an odorless aka "foam safe" CA formulation and those usually are about twice the price of the stinky stuff. I've never used them but I do believe they are slower to set up and that may explain the extra open time and willingness to mix with tints.
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