[Hallicrafters] Brightening Cadmium Plated Chassis

[GARDGORE at aol.com]

Hallicrafters used cadmium plated steel chassis that the metal finishers and 
platers refer to as "clear cad" whatever that is. For whatever reason that 
particular type of cadmium plating often did not stand the test of time well 
but a darkened or tarnished appearance can be vastly improved. On many of the 
Hallicrafters rigs I clean up and recondition here I usually disassemble 
everything as much as is practical in order to do a better job. Often I send 
discolored cadmium parts out to be replated. Due to economics and 
environmental concerns it is getting difficult to find metal refinishers that 
still do cad plating. Most have converted their cad tanks over to zinc 
because zinc tanks are less labor intensive and easier to maintain for them 
and many of their previous cad customers are OK with zinc now anyway. In my 
opinion a zinc finish will not look right where cad was used originally by 
Hallicrafters. Even if you get covers, side braces, brackets and tube shields 
replated you still have the chassis to clean. On some really grimy rigs that 
have badly discolored chassis you should just plan to get serious with the 
cleaning if a brighter more presentable rig is what you want. I have been 
there before with the Q-Tip deal and that gets old real fast. There is a 
better way and it involves getting the chassis wet but if you are 
knowledgeable and careful about what you are doing the results are worth the 
effort and no harm will be done. Start with a complete disassembly by 
removing as much as possible from the chassis. I use muffin pans to organize 
hardware items as they are removed. Next tape over holes in IF cans and cover 
transformers with plastic bags secured with rubber bands to prevent moisture 
getting in where you don't want it. Next (I recommend working outside on a 
cardtable) mix up some sodium bisulfate in warm water (teaspoon of granules 
to a cup of water) and with rubber gloves using brushes and shop rags scrub 
the chassis where needed. Be sure to tape over the metal band on the brush to 
prevent scraping the sides of the IF cans etc. Next using a 50-50 mix of 
ammonia and 409 in a plastic sprayer bottle and with brushes and water scrub 
over the area that was worked with sodium bisulfate and rinse with water. 
Next using a strong shop vac with the hose and nozzle on the blowing side, 
blow dry both sides of the chassis and leave out in the sun the rest of the 
afternoon to be sure everything is completely dry. Next believe it or not 
spray the top of the chassis with WD-40 and begin buffing with shop rags. As 
you polish the metal will appear to get darker, don't be concerned about that 
for now, just keep on rubbing, your cloth will get dark, let it get dark. 
Next with OZ polish saturate a shop cloth and wipe down the chassis to clean 
off the dark residue left behind from the WD-40 step. You should now see 
sparkling bright cadmium surface that looks almost like new. Reassemble as 
necessary, sit back and admire your work.

Regards, 
Greg Gore; WA1KBQ
Charlotte, NC

1) Sodium Bisulfate is commonly known as pH Down for swimming pools. It is 
available at most local stores in the swimming pool section and comes in a 
pint size bottle for $2 or $3.
2) Every BA hobbyist should have a pint of OZ polish on hand. Perfect for 
rejuvenating old crackle paint finishes, knobs, bakelite parts, plastic parts 
and chassis as mentioned. Use instead of the usual snake oil. Milky white and 
goes on as a liquid but it dries to the touch to a satin appearance, not 
shiny. Contains no silicones, does not permanently alter anything and is 
reversible if desired. Available from Constantines (NY and FL) a wood 
refinishers supply house. Don't remember their number but you can probably 
find them on the internet (try a search at www.google.com)
3) Try the above on a cad plated piece of scrap first to get the hang of it.