Official Luthiers Forum!

Hi All,
thought I'd give royal-lac a try on a sitka/black walnut OM I'm finishing up. So far, I really like the application process (brush on, over several layers of seal-lac). Every thing was going fine through 6 coats, flat sanding, and adding several more coats until.... I put a shop light behind me to help illuminate while applying top coats, to help see where I've been and where I need to go. When done, I left the light shining on to perhaps helps speed the drying. (light 4-5 feet away, regular halogen shop lights, probably bathed guitar in 75-80 degrees, not too hot) When I came back in an hour, the lac was dry to touch, but had a couple hundred little "bubbles" raised on the sides. (not just the side by the lamp, but both sides.) Top and back were flat and smooth and dry. Any advice as to what might have happened? Did that little added warmth cause off-gassing at a rate that bubbled the finish? I'm planning to level-sand this down with 400wet, then hopefully lay down some more top coats if that sounds reasonable. Just for curiousity sake, since I need to wait at least overnite before level sanding, I went ahead and brushed on one more coat in hopes that it may blend-in with the bubbles and help smooth them out at best, or at worst, make me level sanding job just a little longer tomorrow? Any thoughts or similar experiences? I tried to take a picture, but really couldn't capture the true essence. I couldn't tell what it was by the way the picture came out. If anyone is familiar with boats, it looks like hundreds of tiny, 1mm barnacles on the side of the guitar! Which is what makes me think it has something to do with gas escaping.

thanks--Dave F

ps...just for completeness, the sides and back are black walnut twice filled with z-poxy and sanded down to wood up to 320 hopefully only leaving poxy in the pores. 5 coats of seal-lac, sanded down to 400wet prior to 6 coats royal-lac, then level sanded with 400wet again. this happened after 3 coat after that. (9th total topcoat)

David, it sounds to me like contamination. Do you have any silicone in the shop?

_________________
Jim Watts
http://jameswattsguitars.com

Sounds like maybe solvent pop..... Any drafts in the area? How thick are you applying the shellac?

_________________
Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/

No silicone allowed downstairs, and I can't think of any contact whatsoever. No drafts, even to a fault. Only thing I can think of was the shop light, but it really didn't even make the body warm to touch. Spent a looooong time level sanding bumps out, but think I avoided any sand-throughs to wood.

I am with Brian... Sounds maybe like the shellac was too thick and skinned over too fast. Especially with the light warming up things.

Here in South Carolina - I have all sorts of trouble with finishing when the weather gets too hot.... I basically can't spray when it's hot... Brushing - I generally have to use a lot more thinner...

I will never use Royal Lac again. I did 5 instruments with it only to develope alligator skin finish on all of them. I sanded them all back to bare wood and finished with nitro. Get that stinking Royal Lac away from me.

_________________
Michael F Smith
Goat Rock Ukulele
http://goatrockukulele.com

I have finished several guitars using Royal Lac to French polish the instruments. It has worked great for me, and has much more durability than regular shellac. I have not had any issues with any kind of finish separation or checking.

_________________
Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

I may try cutting it a little bit to thin it down. The solvent pop Brian and Truckjohn mention may be the problem. Thanks.
This learning curves is much steeper than I thought!

I've done a couple no problems. Very durable. It's all I use to French polish with now.

And I would also keep it out of the lights/heat so it doesn't skin over too fast while the stuff underneath is still a bit gooey...

I tried brushing it, but did not like how it went on. When I switched to French polishing it on, everything got a lot better. I mention this because: If the problem here was that the finish was applied too thick, you should not have that problem if you pad the finish on in the French polish manner.

RoyalLac is sensitive to how you apply it. If you try to spray and follow a nitro type schedule you will have problems. I have been working with this finish for a while and have experienced some of the application problems. If you pore fill, you should sand back to the wood and leave the filler only in the pores. Seal with several coats of SealLac then do your finish with RoyalLac. If spraying to not let it go on dry but spray wet coats. No more than 4 coats in 8 hours evenly spaced but I would do two coats 4 hours apart and then wait till the next day. I don't brush anything so I can't comment on that. In spite of the problems I experienced I have come to realize my application process was the problem and when it's done right it's a beautiful finish. I am now french polishing with it from now on.

If you contact the manufacturer their customer service is superb and they can advise you on your finish schedule.

_________________
Steve Smith
"Music is what feelings sound like"

I have used Royal-Lac on a handful of guitars. Almost always if there is a problem it is because I have gotten impatient and tried to apply too much at one time. However, I think that is true for any shellac application --not a Royal-Lac issue. It really is about doing dozens and dozens of applications with a near dry applicator. Fortunately, it dries so quickly that you can work a back, sides, front and immediately start on the back again. Still, it is hours and hours of rubbing an applicator on the guitar. I struggle with finding the patience and time. The alternative of spraying may take much less time, but is full of its own miseries.

Thanks again. Got some work to do! I've found one of the hardest parts of this luthiery gig, is learning to accept imperfection, and move on. Life is not an O'Brien video!

Yeah, that's a tough one. There is a judgment call to be made on a case by case basis. Sometimes, you are better off letting the imperfection stay there and moving on. The guitar shows some scars from your imperfect skills, but it works as a guitar, and you will know better next time. Other times, the part you are making is better off scrapped so you can start over and do it better this time. I sweat over those decisions.

The part that always surprises me is that often what I consider to be glaring flaws, nobody else even sees - often even other luthiers and they are usually the most discerning bunch.

_________________
Steve Smith
"Music is what feelings sound like"

"I will never use Royal Lac again. I did 5 instruments with it only to develope alligator skin finish on all of them. I sanded them all back to bare wood and finished with nitro. Get that stinking Royal Lac away from me."

How did you apply it and when did it alligator?