Mullard MAS3 - UK Vintage Radio Repair and Restoration Discussion Forum

Magic Eye · 13th Jun 2015, 8:58 pm

Hi all
I have just acquired this radio which dates from 1936. The owner had previously confirmed that the cabinet had been stripped. When I picked it up he told me that the finish was so bad he thought he would strip it using a power sander

Having got it home the case has a small clump of worm holes which I will treat. Fortunately it doesn't seem to have faired too badly at the hands of the sander, with only a hint of thin veneer at some corners.

Can anyone advise me what the original finish was on these sets, was it coloured lacquer? Would it be best to apply Danish oil to the cabinet, given that my restoration skills are probably best described as "beginner"!

grateful for any advice
Jon

stevehertz · 14th Jun 2015, 12:48 pm

Jon, it's a bit of a long standing myth that vintage radios were finished in french polish, shellac and many other 'exotic' finishes. Some, or even many of the 1920s sets maybe, but I can say with complete confidence that virtually all sets from the thirties onwards would have been finished using cellulose lacquer - we're talking mass production, and french polishing is not that. Much later - I'm not sure when exactly but probably the early 60s - polyurethane finishes would have been brought in as well. Danish oil is a 'suitable' method to refinish a set with, but why when cellulose is readily available in liquid and spray can forms?

The cabinets, if not made in house - as they would have been by some of the larger (wireless) manufacturers - would have been made my outsourced cabinet makers. The veneer would have either been stained/dyed prior to the application of clear cellulose or, coloured cellulose may have been used or, a combination of both to attain various shades and effects. By the mid thirties, cabinet designs were a high priority as manufacturers fought for business in competitive markets and if you look at cabinets of that period they often are multi-coloured in various shades of exotic wood.

Liberon is a stain/dye sold by Screwfix http://www.liberon.co.uk/dyes/spirit...0xNzgmfA%3D%3D , and cellulose lacquer itself can be bought from many places - just google it or look at auction sites. I'd take a look at photos of your set (google it's name and model and look under 'images') and basically try to match the colour using stain and cellulose. You can add drops of stain into cellulose lacquer BTW. If you want it original - and you seem to suggest that you do - then cellulose is the only way to go.

David G4EBT · 14th Jun 2015, 6:42 pm

Yes, it will almost certainly originally have been sprayed with 'toner' then in the 1930s (before acrylic lacquer came into use) will have been sprayed with nitrocellulose lacquer.

In terms of how best to finish it now on a DIY basis, Danish oil is easy to apply and needs little skill, but bear in mind that oil finishes penetrate the wood and don't just 'dry' - they go through a chemical change when they combine with oxygen and polymerise, so if you later want the cabinet to look darker, you're stuck with what you've got. Hence, if you want a darker finish, you need to apply toner or dye first. To apply Danish oil wipe it on and wipe it off - don't be tempted to lather it on in a thick coat and leave it there or it will just wrinkle up as it cures. If you leave Danish oil to cure for 24 hours between coats and give say three coats, then polish with paste wax you'll get a nice sheen, but you can't simply keep applying more and more coats to build up a finish as you could with varnish, lacquer or shellac.

The other alternative to Danish oil (which is basically a mixture of tung oil, raw linseed oil and resins) is lacquer, as mentioned by Steve. I've mentioned before that water based acrylic lacquer as used as the final coat over metallic car paint these days is easier to use than lacquer applied by brush, and is widely available in 400 mL aerosols. If you intend to use stain to darken the cabinet first, do make sure that it's water based stain - not spirit based or the lacquer (whether acrylic or nitrocellulose) will just sit on the wood rather than to penetrate it.

If you want the sort of finish that musical instruments such as guitars have, you can buy pre-catalysed nitrocellulose lacquer in 400 mL cans, enough to give two or three coats to your cabinet. EG:

http://www.tonetechluthiersupplies.c...r-aerosol.html

Lucky that the sander didn't wreck the cabinet - veneer is only 0.6mm thick and it's so easy to cut right through it.

Hope that helps a bit.

Magic Eye · 15th Jun 2015, 11:08 pm

Thanks Steve and David for your advice.
Looks like I have a few options when it comes to refinishing. For now I need to deal with the small amount of woodworm.

Regards
Jon

stevehertz · 16th Jun 2015, 11:02 am

For woodworm, use proprietary woodworm fluid in an old hyperdermic needle, cut most of the 'needle' off, and insert it into as many holes as you can, and literally force the fluid into the holes and surrounding wood. Just painting or spraying woodworm fluid on to the wood gets nowhere near as much penetration as does the above, it's very effective. I did it on a Philips 634A in the 70s and to date not a single extra flight hole has appeared.

I fill the flight holes with the nearest shade of plastic wood and then touch them in with artists' felt tip pens to become the right colour. You can buy them in various shades of brown and they are available from artists shops - not cheap though.

13th Jun 2015, 8:58 pm	#1
Magic Eye Pentode Join Date: Oct 2009 Location: Shaftesbury, Dorset, UK. Posts: 179	Mullard MAS3 Hi all I have just acquired this radio which dates from 1936. The owner had previously confirmed that the cabinet had been stripped. When I picked it up he told me that the finish was so bad he thought he would strip it using a power sander Having got it home the case has a small clump of worm holes which I will treat. Fortunately it doesn't seem to have faired too badly at the hands of the sander, with only a hint of thin veneer at some corners. Can anyone advise me what the original finish was on these sets, was it coloured lacquer? Would it be best to apply Danish oil to the cabinet, given that my restoration skills are probably best described as "beginner"! grateful for any advice Jon Attached Thumbnails

14th Jun 2015, 12:48 pm	#2
stevehertz Dekatron Join Date: Sep 2011 Location: Rugeley, Staffordshire, UK. Posts: 8,835	Re: Mullard MAS3 Jon, it's a bit of a long standing myth that vintage radios were finished in french polish, shellac and many other 'exotic' finishes. Some, or even many of the 1920s sets maybe, but I can say with complete confidence that virtually all sets from the thirties onwards would have been finished using cellulose lacquer - we're talking mass production, and french polishing is not that. Much later - I'm not sure when exactly but probably the early 60s - polyurethane finishes would have been brought in as well. Danish oil is a 'suitable' method to refinish a set with, but why when cellulose is readily available in liquid and spray can forms? The cabinets, if not made in house - as they would have been by some of the larger (wireless) manufacturers - would have been made my outsourced cabinet makers. The veneer would have either been stained/dyed prior to the application of clear cellulose or, coloured cellulose may have been used or, a combination of both to attain various shades and effects. By the mid thirties, cabinet designs were a high priority as manufacturers fought for business in competitive markets and if you look at cabinets of that period they often are multi-coloured in various shades of exotic wood. Liberon is a stain/dye sold by Screwfix http://www.liberon.co.uk/dyes/spirit...0xNzgmfA%3D%3D , and cellulose lacquer itself can be bought from many places - just google it or look at auction sites. I'd take a look at photos of your set (google it's name and model and look under 'images') and basically try to match the colour using stain and cellulose. You can add drops of stain into cellulose lacquer BTW. If you want it original - and you seem to suggest that you do - then cellulose is the only way to go. __________________ A digital radio is the latest thing, but a vintage wireless is forever..

14th Jun 2015, 6:42 pm	#3
David G4EBT Dekatron Join Date: Feb 2003 Location: Cottingham, East Yorkshire, UK. Posts: 5,766	Re: Mullard MAS3 Yes, it will almost certainly originally have been sprayed with 'toner' then in the 1930s (before acrylic lacquer came into use) will have been sprayed with nitrocellulose lacquer. In terms of how best to finish it now on a DIY basis, Danish oil is easy to apply and needs little skill, but bear in mind that oil finishes penetrate the wood and don't just 'dry' - they go through a chemical change when they combine with oxygen and polymerise, so if you later want the cabinet to look darker, you're stuck with what you've got. Hence, if you want a darker finish, you need to apply toner or dye first. To apply Danish oil wipe it on and wipe it off - don't be tempted to lather it on in a thick coat and leave it there or it will just wrinkle up as it cures. If you leave Danish oil to cure for 24 hours between coats and give say three coats, then polish with paste wax you'll get a nice sheen, but you can't simply keep applying more and more coats to build up a finish as you could with varnish, lacquer or shellac. The other alternative to Danish oil (which is basically a mixture of tung oil, raw linseed oil and resins) is lacquer, as mentioned by Steve. I've mentioned before that water based acrylic lacquer as used as the final coat over metallic car paint these days is easier to use than lacquer applied by brush, and is widely available in 400 mL aerosols. If you intend to use stain to darken the cabinet first, do make sure that it's water based stain - not spirit based or the lacquer (whether acrylic or nitrocellulose) will just sit on the wood rather than to penetrate it. If you want the sort of finish that musical instruments such as guitars have, you can buy pre-catalysed nitrocellulose lacquer in 400 mL cans, enough to give two or three coats to your cabinet. EG: http://www.tonetechluthiersupplies.c...r-aerosol.html Lucky that the sander didn't wreck the cabinet - veneer is only 0.6mm thick and it's so easy to cut right through it. Hope that helps a bit. __________________ David. BVWS Member. G-QRP Club member 1339.

15th Jun 2015, 11:08 pm	#4
Magic Eye Pentode Join Date: Oct 2009 Location: Shaftesbury, Dorset, UK. Posts: 179	Re: Mullard MAS3 Thanks Steve and David for your advice. Looks like I have a few options when it comes to refinishing. For now I need to deal with the small amount of woodworm. Regards Jon

16th Jun 2015, 11:02 am	#5
stevehertz Dekatron Join Date: Sep 2011 Location: Rugeley, Staffordshire, UK. Posts: 8,835	Re: Mullard MAS3 For woodworm, use proprietary woodworm fluid in an old hyperdermic needle, cut most of the 'needle' off, and insert it into as many holes as you can, and literally force the fluid into the holes and surrounding wood. Just painting or spraying woodworm fluid on to the wood gets nowhere near as much penetration as does the above, it's very effective. I did it on a Philips 634A in the 70s and to date not a single extra flight hole has appeared. I fill the flight holes with the nearest shade of plastic wood and then touch them in with artists' felt tip pens to become the right colour. You can buy them in various shades of brown and they are available from artists shops - not cheap though. __________________ A digital radio is the latest thing, but a vintage wireless is forever..