Black Ink Recommendation

admin · Post by **admin** » Fri Oct 21, 2005 9:29 am

Paul: I am going to proceed with my Epiphone Casino headstock repair and am wondering what type of black ink you recommend for the job? Also in covering the name on the headstock I am going to use tape, again, do you have a recommendation. I am still worried about the nail polish repair. Can I use that much nail polish, is the question?

jingle_jangle · Post by **jingle_jangle** » Fri Oct 21, 2005 10:11 am

Last questions first. Nail polish is basically clear lacquer, but has additives to thicken it, make it more flexible, and to slow its drying a bit.

You can build it up in thin coats, but let each coat harden completely before applying the next. Each coat applied over a hardened coat will adsorb into the previous coats, softening them slightly. So each subsequent coat will take slightly longer to harden.

This is something I used to do over a long period of time (sometimes months), a coat a day.

And that's why I prefer conversion varnish, which can be applied in thicker coats. Caution must be used even here, for if the coats are too thick or the varnish or catalyst are too old, they will have absorbed moisture from the air, and upon curing will release carbon dioxide, in the form of air bubbles.

The black ink I recommend comes from an art supply or stationery store. It's Higgins Waterproof, Number 44011 or 44201, either works well. Be sure to apply it with a good quality soft brush. It will dry with a funny brownish sheen, but when coated with clearcoat will go dead black!

You can tape the headstock name with Scotch Magic Tape. It is a bear to remove, but a bit of help from a sharp tweezers or Exacto-knife tip will get it going.

I don't mask it off on existing logos--I play artist and hand-brush the ink around the letters, a bit at a time, so as not to make a jagged edge. You might want to try this, too. There's a frustrated artist in you, Peter...let him out!!!

admin · Post by **admin** » Sun Oct 23, 2005 5:16 am

And that's why I prefer conversion varnish, which can be applied in thicker coats. Caution must be used even here, for if the coats are too thick or the varnish or catalyst are too old, they will have absorbed moisture from the air, and upon curing will release carbon dioxide, in the form of air bubbles.

Paul: Are these air bubbles likely to remain stable over the course of time or would the finish in that area, having air trapped inside, be more prone to breaking down.

jingle_jangle · Post by **jingle_jangle** » Sun Oct 23, 2005 5:46 am

You would think that the trapped air might hurt the finish stability, but it will not, generally speaking. We~re talking about bubbles in the .1mm size range. Not much air there... The biggest problem is visual, because the surface ones collect dirt and wax and look untidy.

admin · Post by **admin** » Sun Oct 23, 2005 7:19 am

Interesting Paul, thanks. As a follow-up, over what period of time do these gas bubbles form. A period of hours, days or months?

jingle_jangle · Post by **jingle_jangle** » Sun Oct 23, 2005 7:40 am

They form during the catalyzing reaction, as the clear coat polymerizes.

So I guess you could say, "minutes".

By the time the clear coat has gelled, before it's hardened, they are lacked in place. Note that this does not happen during "normal" clear coating, when the clear coat is applied with a spray gun. It happens when a thicker-than normal coating (like a drop) is applied (usually with a brush).

Although the latest versions of these urethanes are not very hygroscopic (water-absorbing), they are not 100% free from this tendency. This means that anything which can add even the most microscopic amount of moisture into the clear coat, should be avoided in the application process. The paintbrush which you use to apply urethane clear coat, should have synthetic, not natural, bristles, and should be absolutely dry.

I should add that this is a minor concern unless the atmosphere and climate are really wet, the clear coat is stale, or both. This will not happen with nail polish.

admin · Post by **admin** » Sun Oct 23, 2005 10:22 am

Paul: Your detailed response is, as always, appreciated. What is the role of temperature in the catalyzing reaction?

jingle_jangle · Post by **jingle_jangle** » Sun Oct 23, 2005 1:37 pm

These reactions are aided by heat, as you might guess. The manufacturer of my conversion varnish, PPG, suggests an elevated temperature cure cycle if speed is important (it isn't to me, and I'll be darned if I'm going to heat my or anybody else's Rickenbacker to 150º just to speed up cure time.

I usually clear coat my guitar finishes as the only work in the day, and do it last thing, too, spending the earlier part of the day cleaning my equipment, changing filters, and setting up carefully. Clear coating is a Zen thing...

Then, within 10 minutes it's what is called "dust free", meaning that it is no longer sticky to the touch, although it's far from hardened. It's about 90% hardened by next morning. This is a good time to do the first round of color wet sanding, to open up the clearcoat and allow it to degas and complete its hardening cycle. The next morning I finish color sanding and buffing.

A typical color sanding cycle on a guitar--I do it all by hand--begins with #1000 grit and progresses through 1500 to 2000. It is then ready to buff, first by machine, and finally by hand. The entire color-sanding/buffing process takes between 4 and 6 hours for one guitar.

Oh, you asked about temperature. Well, the answer is up there somewhere in the beginning.