Mike's Oud Forums

Polyurethane over shellac?

Jonathan - 8-19-2010 at 07:39 AM

Does anybody out there know if I can use polyurethane over shellac?
I am finishing up oud #5, and have a few coats of shellac on it. It looks fine, but I would really like to put some polyurethane over it for durability. Any thoughts?

Thanks!

spyrosc - 8-19-2010 at 08:32 AM

Yes, it's doable.

Spyros C.


Yes, but be carfull

Yaron Naor - 8-19-2010 at 09:27 AM

You can do it... but note that any oil or fingerprints on the shellac will cause you trouble, (orange skin)
Ether you clean it very good with baby wipeons
Or you can clean the Shellac with alcohol and than apply the finish

In both option, spray a fast and thin first coat and than proceed

See the attached image of semi mat polyurethane finish over shellac

Good luck!
Yaron

DSCN3413 (Medium).jpg - 120kB

Abo Zaina - 8-21-2010 at 11:44 AM

I was thinking of such idea but only for the bowel to protect it from my excessive sweating :mad: ( it reaches 50 during summer where I live)
theoritcally I don't think this will affect the sound but I was hesitant because of I'm not sure if it is possible.
and I have the glossy wipe-on poly I'm not sure about the quality of the finish since it is mostly applied by spraying poly.
I'll try it on a piece of wood then if im happy with the results I'll go for it

fernandraynaud - 8-21-2010 at 12:38 PM

Since it goes on top of an existing finish you'll also have to try it in a least obvious corner of the bowl. Some varnishes are more compatible than others and you can end up with all sorts of swampy messes. You also need to thoroughly clean the surface first, and that needs testing too, as alcohol dissolves some finishes, acetone dissolves others.



Jonathan - 8-24-2010 at 10:44 AM

Thanks a lot guys!
5 coats of shellac, and so far a couple of coats of polyurethane. It's looking sharp. I'll post some pics when I'm done.
As always, I real appreciate the help

FastForward - 8-24-2010 at 11:19 AM

Hi Jonathan, I was reading about this the past couple of days and it seems that generally there shouldn't be a problem as long as you made sure to use dewaxed shellac and that you cleaned any possible oily residue.

Looking forward to seeing the finished oud.

SamirCanada - 8-24-2010 at 01:43 PM

Good stuff Jonathan.
looking forward to see the pics too! your latest instrument was stunning my friend.

did you notice any difference between the drying times of the poly when applied over shellac?

If it doesn't thoroughly dry you might have problems with the wax in the shellac preventing the adhesion of the polyurethane.

let us know.

Jonathan - 8-24-2010 at 04:04 PM

Thanks Samir
No problems thus far, but it was a couple of days after the last coat of shellac become I put on the first coat of poly.
I haven't really used poly much in the paast. I did restore an oud, and did use poly alone (no shellac) with decent results, but I really love the look of shellac--that little bit of amber just gives the wood such warmth.