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Does Royal-Lac (shellac) age and wear like Nitrocellulose?
http://luthiersforum.com/forum/viewtopic.php?f=10101&t=51946
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Author:  SteveSmith [ Mon May 20, 2019 9:31 am ]
Post subject:  Re: Does Royal-Lac (shellac) age and wear like Nitrocellulos

Since I had the crazing issues with spraying RL, I corresponded with Vijay quite a bit to sort out my problems. Since then I've done two with regular RL FP'd, one is about 2 years old and is fine, the other is relatively fresh. Dry sanded, shop is maintained right around 45% RH. I seal with Aqua Coat over shellac. I have a sanding booth with explosive proof fan, etc. so I can spray whatever I want but I much prefer the French polished Royal Lac. I build what I want and I don't do commissions any more - more of a take it or leave it approach so I don't have to worry about customer requirements.

Author:  guitarjtb [ Mon May 20, 2019 10:59 am ]
Post subject:  Re: Does Royal-Lac (shellac) age and wear like Nitrocellulos

SteveSmith wrote:
Since I had the crazing issues with spraying RL, I corresponded with Vijay quite a bit to sort out my problems. Since then I've done two with regular RL FP'd, one is about 2 years old and is fine, the other is relatively fresh. Dry sanded, shop is maintained right around 45% RH. I seal with Aqua Coat over shellac. I have a sanding booth with explosive proof fan, etc. so I can spray whatever I want but I much prefer the French polished Royal Lac. I build what I want and I don't do commissions any more - more of a take it or leave it approach so I don't have to worry about customer requirements.



I agree. For each new guitar I build, I probably restore 10 to 15 vintage guitars. Most are complete rebuilds, so it is like building a guitar, using old Gibson, Martin, or Harmony parts, and not having to do any finish work. Like you say, it is a take it or leave it approach.

Author:  jfmckenna [ Tue May 21, 2019 8:07 am ]
Post subject:  Re: Does Royal-Lac (shellac) age and wear like Nitrocellulos

Oh yeah I forgot that some people had issues with the finish checking after spray application. I just padded it on the few guitars I've used it with. But even there time will tell. My guess is that if you attempted to use RL and purposely go for a finish checked look you wouldn't achieve it.

Author:  sjfoss [ Tue May 21, 2019 9:32 am ]
Post subject:  Re: Does Royal-Lac (shellac) age and wear like Nitrocellulos

James, Trevor,

The wet sanding was with straight water, in between polishing (and in one case padding) sessions. iIRC, Vijay said that the water MUST come out and covering up with more shellac just means it'll come out later after you are "done" with the finish. For me, the crazing showed up 6 - 9 months later.

Up to that point, I had french polished and padded, but not sprayed. And, being an amateur, I've only used this on 6 guitars. The last one I sprayed post-cat RL; this guitar was for a friend's nephew and I haven't heard from nor seen it since. By that time, I was not using water during sanding.

I"ve re-finished the guitars that experienced the crazing using the same product, but without wet sanding. In the 3 years since, They still look fine.

I like this product.

Steve

Author:  WaddyThomson [ Tue May 21, 2019 10:51 am ]
Post subject:  Re: Does Royal-Lac (shellac) age and wear like Nitrocellulos

I have never had any crazing with my Royal Lac finishes. That said, I never wet sand during the finish process except at the end. I build using French polishing or wiping on coats. Both work just fine. If I do sanding between coats, it's dry sanding.

Author:  SteveSmith [ Tue May 21, 2019 11:03 am ]
Post subject:  Re: Does Royal-Lac (shellac) age and wear like Nitrocellulos

Vijay told me that if I wanted to wet sand I should wait 30 days.

Author:  guitarjtb [ Tue May 21, 2019 11:08 am ]
Post subject:  Re: Does Royal-Lac (shellac) age and wear like Nitrocellulos

sjfoss wrote:
James, Trevor,

The wet sanding was with straight water, in between polishing (and in one case padding) sessions. iIRC, Vijay said that the water MUST come out and covering up with more shellac just means it'll come out later after you are "done" with the finish. For me, the crazing showed up 6 - 9 months later.

Up to that point, I had french polished and padded, but not sprayed. And, being an amateur, I've only used this on 6 guitars. The last one I sprayed post-cat RL; this guitar was for a friend's nephew and I haven't heard from nor seen it since. By that time, I was not using water during sanding.

I"ve re-finished the guitars that experienced the crazing using the same product, but without wet sanding. In the 3 years since, They still look fine.

I like this product.

Steve


Steve,
How did you remove the old finish?
When you re-finished the guitars, did you seal with Seal Lac?
Thanks for your help.
James

Author:  sjfoss [ Tue May 21, 2019 12:19 pm ]
Post subject:  Re: Does Royal-Lac (shellac) age and wear like Nitrocellulos

James,

I used 220 grit to sand it back to wood. I sealed the wood with straight 1-lb cut shellac (from Vijay; I believe that seal-lac is 2-lb cut) and re-did everything using my same process but without any water.

At this point, I consider the re-finish to be "tuition" in a semester of finishing.

Steve

Author:  meddlingfool [ Tue May 21, 2019 2:09 pm ]
Post subject:  Re: Does Royal-Lac (shellac) age and wear like Nitrocellulos

Waddy,

How did you manage to pad or do wipe on coats? For me, even heavily diluted, it was a non starter...

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