Difficulty with drop fills

[david ericson]

I recently tried the drop fill technique on a couple finish scratches on my guitar, after the superglue was applied and had dried there was still the white discoloration of the scratch underneath the glue. What should I have done differently and what can I do to fix the now superglue covered scratches on the guitar?

[Mike Kolb]

The purpose of the drop-fill method is to build the top finish back up over a repaired color finish.  Hard to tell from the picture but, in this case, it appears that the color just wasn't there when the CA was applied.  

Typically, you'd want to do all the coloring work first, then build the clear top finish however you're going to do it.  So what to do now?  

It's never going to be invisible unless you opt to redo the entire body. Other than that, there's almost no alternative except to carefully remove the CA, match the color in the damaged area and start the drop-fills again. 

[david ericson]

Thanks for the reply, Mike. Is it necessary to use color even when the damage to the finish doesn't reach the wood? 

[Paul Verticchio]

That appears to be an instrument finished in ploy.

I don't know if it's ever been brought up, but CA drop fills on poly finishes do not meld into the substrate as it does on lacquer finishes. It's almost always a visible repair.

Also, if the guitar is/was not properly prepped (all contamination, polish, oil etc, removed), they usually look worse than the original 'ding'. I offer drop fills NOT as cosmetic restorations, but only as a 'protective' service to keep them from worsening. They are not a favorite task of mine. One philosophical problem I have is charging a fee that covers my time without exceeding 50% of the value of the poly finished instruments that come in. Drop fills on poly are more time consuming than using CA or lacquer on a 'hot finish'.

Keep trying as practice makes you a better and more experienced craftsman :) Good luck.

[david ericson]

That makes sense, thanks for the help Paul.

[Mark A. Kane]

David,

If your instrument is indeed finished in poly, and you have super glue solvent on hand, you can remove the cured super glue without too much trouble. It may take a few tries but if you are careful and diligent you will have success. You can then use any number of tools or techniques to clean the scratch out moderately deeper than it was to begin with. Repeated rinsing with acetone (with a Q-Tip) while digging into the scratch will remove the swarf and clean the scratch out simultaneously. Once you have a clean trough, start again with fresh, thin super glue, and go at it sparingly. Several layers may be necessary. I'd stay away from using an accelerator if you have limited experience with it. Just be patient. This is a job I've done countless times with decent (not perfect, but almost) results. 

[david ericson]

Thanks for the advice Mark! I'll definitely give that a try.