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I french polish my instruments with shellac and have no experience with nitro.

Is it possible to repair a blemish in a nitro finish with shellac ? I am looking at a 1/4 x 1/8" spot on the neck of a recent National where the surface of the nitro was rubbed off. Can I do a little french polish with a q-tip over the bad spot, or should I be looking at a different technique to repair ?

-jd

You could use FP but I personally would use Nitro because it will burn into the old finish whereas FB will set on top of it. Besides FP is softer and will wear away faster than nitro.

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tim...
http://www.mcknightguitars.com

Sorry, I didn't correctly separate my reply from your original post.

Virtually all the recent-era instruments other than a few one-offs would have a water-base finish, very often Crystalac. Does the neck have a generally slightly pebbly feel? What's the date on the label in the body?

If you are speaking spot repair you will get a noticalble difference in the finish appearance at the repair and likely witness lines. If you are speaking FP over the total top. Tha is more than doable with proper prep but like Tim said why not use nitro so that the burn in is good.

I have to find the label to determine the age. This is a brass body 14 fret, so it would have to be in the last couple of years... Info packet in the case had the standard disclaimer about finish interacting with vinyl -which is why I assumed it was nitro. This would be a spot repair on the neck where a defect in the case caused finish damage.

if it is a water-based finish, what is the preferred repair technique ?

thanks,

-jd

Its doubtful it is water based. Lacquer is typically sprayed over brass to keep it from tarnishing. I would suspect of they used nitro on the body that the neck has the same finish. Water based finishes don't react with rubber, that I am aware of.

WB finishes can be repaired by first scuffing with 400, spot spraying, wet sanding followed by buffing. However it is common to have witness lines show up around the spot repair. You can shoot a coat of DA prior to applying the WB finish to reduce witness lines.

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tim...
http://www.mcknightguitars.com

If waterbase then a copatable waterbase I personally think due to the warning you mentioned that the finish is nitro but you really should test first to make sure.

It is 2009, so I assume waterbase, will need to test with acetone to be sure.

Don't know why the warning about reacting with vinyl...

It is a very nicely set and sounds great.

-jd

Few if any factory guitars are finished with waterborne finishes. Most are finished with either a cat poly or nitro i know of no manufacturer using WB but there may be some.

Ditto... ^ What he said

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tim...
http://www.mcknightguitars.com

The necks and wood-bodies on Nationals were indeed finished in water-base since the early 90's. Many were
crystalac, though they may have moved to another finish. You can try spot sanding, color-matching if
necessary, then brushing on thin coats of Crystalac cut with a *small* amount of acetone. Crystalac burns in
fairly well (unless the formula has been changed ).

Learn somthing new every day I did not know that and I must say it really surprises me for National. .Not doubting just surprised