Renewing nitro varnish

[viento]

I have to renew the slightly scratched varnish of the EIR sides and back of an acoustic guitar.

Would it be sufficient to grind the old paint with 320 or 500 grit sandpaper
before spraying new nitro laquer layers?
I´d prefer using 500 grit because it causes less visible scratches.

[mirwa]

If it is nitro, any grit you want, the new nitro melts/fuses into the old layers

Painting a Hd28 necktoday, prepped with 400grit
Painting a CEO7 back, prepped with 1000 grit
Painting a les Paul neck, prepped with 400
Painting another les paul neck, but its been colour coated already so 1000grit

Add to that i have a ricky getting a full 2 pack paint job today

I do a lot of painting.

Here is yesterdays load in the paint booth.




Steve

[viento]

Steve, thanks for your information.
I´ll continue sanding with 500 grit.

The only problem I have to solve is connected with the small abalone ring around the sound hole.
Only for the top I want to spray transparent vintage yellowish amber color and I dont know
how to protect the abalone ring from getting tinted too. A slight hue would be ok but not more.
The rest of the guitar will be sprayed with clear nitro.

[mirwa]

apart from masking it up, your other option is spray 6 coats clear just on the rosette/abalone, then proceed with refinishing the guitar with typical amount of lacquer.

After lacquer drys, wet sand your rosette area, sand until the tinted finish is gone, should even out fairly well

Steve

[viento]

Thanks!
Masking the abalone is a bit difficult because it is only a quarter of an inch wide.
But with much patience and clear masking tape and a razor knife I will make it.

I´ll give it a try.

[KimR]

Find an Automobile Paint Supply company and you can buy special tape that comes in 1/4 size. Works better than regular tape as it does not fuzz up. Not cheap but worth it for special projects.

[viento]

Thanks for your info!
Can that tape be bent without any wrinkles / folds ?

[KimR]

For the most part, yes. Everything has it's limits. There is also a 1/8 tape. I have used it for a burst on a J-45 clone for both abalone ring and to protect the binding and am happy with results.

[viento]

......

[mirwa]

Whenever i need a nice edge, I use pin striping tape, its 3mm wide, i shape it to whatever contour is needed and then back fill with normal low tack tape

Steve

[viento]

Thanks Steve, that´s what I will do.

In addition I guess a first layer with clear nitro
will prevent the tinted nitro from creeping under the tape.

[Quickstep192]

Originally Posted by mirwa

If it is nitro, any grit you want, the new nitro melts/fuses into the old layers

Steve,

I’ve found that if I sand with anything less than 1500 that I can see the sand marks through the finish. Ant thoughts on where things are going wrong for me?

[mirwa]

Are we talking nitro or something else?

[viento]

Originally Posted by Quickstep192

Steve,

I’ve found that if I sand with anything less than 1500 that I can see the sand marks through the finish. Ant thoughts on where things are going wrong for me?

Yes, that´s awful - much more work with finer grit!
And their lifespan is shorter even with "Mirka Abranet" ("lattice linen"?) - I don´t know what that´s called in the US.

[Quickstep192]

Originally Posted by mirwa

Are we talking nitro or something else?

Yes, nitro. Behlen’s Stringed Instrument Lacquer