Official Luthiers Forum!

I recently inherited one of my original falcate classical guitars. Sadly my classical guitar teacher died. I have its sister built right before as one of my daily guitar. Both finished with padded on Royal Lac. My guitar's finish is still in good shape while my instructors guitar had quite a few rough spots with the finish crazed in some areas. I went back to my notes and found out my instructors guitar was pore filled with zpoxy while I used West System 105 epoxy with a 207 hardner for my guitar. Just 2 data points but one does not often have the ability to compare 2 decade old guitars.

After Royal Lac cures new finish will not melt into it. I did not want to strip the finish so I sanded back the finish a bit using 600p until smooth to the touch. I then wiped on a thin coat of gluboost fill and finish thin, sanded back, another coat, sand again and then I French polished with regular shellac. The CA seemed to fill the remain finish cracks and a few open pored. I figured the CA would stick to the old Royal Lac and I know shellac sticks to CA. looks good now. I will come back in another decade with the new results.

_________________
http://www.Harvestmoonguitars.com

You’re off Royal Lac?

Thanks for the info. Back in the day I finished a few necks with TruOil over a Z-Poxy fill. They all got fuzzy and it took sanding back to wood and refinishing to fix. Something about amines leaching out but I quit using Z-Poxy. That might have been the problem.

_________________
It's not what you don't know that hurts you, it's what you do know that's wrong.

I spray postcat Royal Lac but over Silver tip or West Systems pore fill. I am off of Zpoxy. As Terence suggest Z poxy tends to leave more amines. Maybe I used to much hardener. I think after I started using system 3 and west system I was carefully weighing the resin and hardener.

_________________
http://www.Harvestmoonguitars.com

I had fuzz problems on water based finishes with Z poxy as well…

Quick one - did you wipe the Z poxy with water after each application and before sanding the layer?

_________________
The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

I did not. This was quite some time ago so memories are vague…

The excess amines that are left on the surface need to be removed with detergent and water. Even then, as well as mechanical abrasion, we saw occasional issues with down-stream separation with male players that sweated quite a bit. We hypothesized that lower-pH perspiration (males are typically lower/more acidic in pH value of their actual sweat) was the mechanism that generated the problem. Using SilverTip or other non-blushing epoxy filler was a full solution. Endurovar I over Zpoxy also worked well to limit separation (although that may have been more the case that our players were not super-sweaters) but Silvertip filler eliminated the issue entirely.

I am one of those male sweaters who has destroyed the finish on the neck of some of the guitars I played regularly. I blamed it on my body chemistry and on EMTECH EM6000 ability to withstand me. Thinking about it now that was during my Zpoxy days.

_________________
http://www.Harvestmoonguitars.com