Thread: Ozuku JNat: problem using shellac

Originally Posted by wsfarrell

Here's a different point of view:

I was having some issues using water-based lacquer to seal a stone, so I posed a question to the stone's seller (an acknowledged expert who's dealt with literally hundreds of Jnats, whose privacy I'll respect). He said he never seals his stones, as he prefers them to look natural (duh). In > 25 years in the business, he's never had a stone delaminate. Sounds good to me.

If you'd like a minimally-used can of Minwax water-based polycrilic, let me know.

I was like that, too, until I had a stone start to develop some cracks. I'd rather try to preempt that if there's anything I can do. If I can figure out how to proceed, I may take you up on the offer on that can, thanks

Ok so a little more research and I found out that the stuff I have is NOT wax-free. It's also not easy to let this stuff sit so the wax settles to the bottom, because the company uses some special homogenizing process.
So anyone have any suggestions on where to go from here? Is sanding a bad idea?

Originally Posted by heirkb

So anyone have any suggestions on where to go from here? Is sanding a bad idea?

No need to sand if you want to remove the shellac. It will dissolve in methylated spirit.

Did the original coats dry hard ? Shellac that is past its use by date will not dry properly.

Originally Posted by onimaru55

No need to sand if you want to remove the shellac. It will dissolve in methylated spirit.

Did the original coats dry hard ? Shellac that is past its use by date will not dry properly.

I thought they dried pretty hard. I wasn't easily leaving prints on them. And I remember the expiration date being a year or 2 away...

Wouldn't denatured alcohol damage the stone?

Originally Posted by heirkb

I thought they dried pretty hard. I wasn't easily leaving prints on them. And I remember the expiration date being a year or 2 away...

Wouldn't denatured alcohol damage the stone?

In general you do not want to use shellac that is more than 6 months old

Really? Damn, this can told me to use it if it was less than 3 years old...I'm gonna have to make a trip to Home Depot to get some better sealant, I guess. But I'm not sure if I'll be able to do a coat over the ones I already put down...

Originally Posted by heirkb

Really? Damn, this can told me to use it if it was less than 3 years old...I'm gonna have to make a trip to Home Depot to get some better sealant, I guess. But I'm not sure if I'll be able to do a coat over the ones I already put down...

As far as I know the shellac, which is natural product, goes bad with time and looses its properties. When such shellac gets in contact with water it becomes white and also can peel off. This info I read when I was researching shellac for wood finishing, it also happened with old shellac I used one one of my stones . May be the kind you are using is more durable.

Originally Posted by heirkb

I
Wouldn't denatured alcohol damage the stone?

It is the solvent that the shellac is in anyhow so nope, won't hurt.

Most these materials are moisture cure compounds. Esp urethane's. higher humidity means faster cure times. I don't know your location but here in winter humidity is 0. If the material is still tacky try raising the humidity by misting with some water to activate. It may take more time to cure completely. Esp mulitple coated layers.

Mineral spirits is pretty safe stuff to work with not to harsh a solvent. Try a small sample area first if you want to remove the shellac. Naptha (lighter fluid) is another lower VOC solvent that is relativley mild. BOth will flash off quick Sanding can only be done if it has cured or you will have a mess. A good rule of thumb is when appyling ANY curing compound, always apply some to a seperate piece of substrate so you can observe cure cycle.

I think you better just send that stone too me to fix. We'll get through this..
Mike

[QUOTE=MODINE;727165]Most these materials are moisture cure compounds. Esp urethane's. higher humidity means faster cure times. I don't know your location but here in winter humidity is 0. If the material is still tacky try raising the humidity by misting with some water to activate. It may take more time to cure completely. Esp mulitple coated layers.
QUOTE]


DON'T DO THIS WITH SHELLAC !!!
IT WILL PREVENT PROPER DRYING. Sorry for shouting

Any moisture in the shellac will give you the same results as you have now.