White patch in shellac finish - UK Vintage Radio Repair and Restoration Discussion Forum

JHGibson · 23rd Apr 2006, 9:08 pm

My 1932 Ultra has a whitish patch on the top of the cabinet which seems to be in the interior of the shellac. Is there any way to remove it short of refinishing the shellac?
John.

Aerodyne · 24th Apr 2006, 2:39 pm

This may be moisture. You could try gently applying heat from, say, a hair dryer, but don't overdo it. If it is bloom, the dryer should shift it. The only other way I know is to reflow the shellac -assuming it actually is shellac and not lacquer - by applying methylated spirit on a 'rubber' (a shoe-shaped folding of lint free cloth packed with cotton wool or similar material).
If it is lacquer, it too can be reflowed with specialist thinner but this is no job for the amateur without the proper resources and kit, I feel.
-Tony

lesbuist · 24th Apr 2006, 6:24 pm

Hi

A white patch in shellac finish is similar to french polish problem and is nearly always caused by a heat source such as hot cup which releases moisture in wood under the finish. You can try a heat source such as iron with cloth in between to try and force the moisture out, a more daring option is to put some methylated spirits on affected area and light it. A light rub down with fine sanppare or wire wool and replace the finish shellac/french polish with a rubber.

Les

23rd Apr 2006, 9:08 pm	#1
JHGibson Retired Dormant Member Join Date: Apr 2003 Location: Salt Spring Island, BC, Canada Posts: 368	White patch in shellac finish My 1932 Ultra has a whitish patch on the top of the cabinet which seems to be in the interior of the shellac. Is there any way to remove it short of refinishing the shellac? John.

24th Apr 2006, 2:39 pm	#2
Aerodyne Octode Join Date: Jun 2004 Location: Hampton Vale, Peterborough, UK. Posts: 1,698	Re: White patch in shellac finish This may be moisture. You could try gently applying heat from, say, a hair dryer, but don't overdo it. If it is bloom, the dryer should shift it. The only other way I know is to reflow the shellac -assuming it actually is shellac and not lacquer - by applying methylated spirit on a 'rubber' (a shoe-shaped folding of lint free cloth packed with cotton wool or similar material). If it is lacquer, it too can be reflowed with specialist thinner but this is no job for the amateur without the proper resources and kit, I feel. -Tony

24th Apr 2006, 6:24 pm	#3
lesbuist Retired Dormant Member Join Date: Apr 2006 Location: County Durham Posts: 3	Re: White patch in shellac finish Hi A white patch in shellac finish is similar to french polish problem and is nearly always caused by a heat source such as hot cup which releases moisture in wood under the finish. You can try a heat source such as iron with cloth in between to try and force the moisture out, a more daring option is to put some methylated spirits on affected area and light it. A light rub down with fine sanppare or wire wool and replace the finish shellac/french polish with a rubber. Les Last edited by Darren-UK; 29th Aug 2007 at 12:13 pm. Reason: General tidying.