[Hallicrafters] Nicotine stains

[Barry H]

To call them nicotine stains is a bit of a misnomer.  The nicotine component was safely absorbed through the lungs and into the bloodstream of the afflicted.  Most of what gets attached to things externally is tar, though there is some trace nicotine in it.

First question is whether the unit is military or not.  I have not seen much in the way of non-mil gear that was coated.  Much of the mil gear was coated with a yellow-brownish varnish called MFP -- for mildew fungus protection or maybe it's moisture fungus protection.  That stuff is somewhat hazardous if disturbed as it contains mercury compounds and other nasty stuff (formaldehyde?) in a varnish or shellac base.

The way to tell them apart is to attempt to remove some with a rag or paper towel with solvent, or more safely, liquid cleaner, such as 409 or whatever you have there. Smoke tar will come of rather easily, MFP won't budge.  You can also tell by odor.  The MFP may be odorless or have a formaldehyde odor.  The smoke tar will smell a bit like an ashtray or smoke filled room and be more dicernable when moistened and comes off on the rag.

If it is MFP, do not attempt to remove it.  I does need to be scraped off of solder connections when doing repairs however.  Do not do anything that will atomize it -- cause fine powder particles, as sanding, etc.  

Smoke tar can be readily removed, but make sure that the cure is not worse than the illness.  I have found that tar covered chassis were well preserved underneath.  The poisons in the tar, and trace nictotine apparently act as a preservative and fungus/mildew preventative. After all, nicotine is a natural defense for the tobacco plant -- a poison pill for parasites.  The tar, which is most of the material, acts as a sealer, retarding corrosion, particularly on aluminum, cad plated and unplated metal surfaces.  You'll still want to remove it, but one unpleasant side effect is that some surfaces will start to oxidize after it's removed.  

Also be aware, cadmium is hazardous -- much more hazardous than the virtually non-existent risk from smoke tar deposits, so don't use sandpaper, grind the stuff or snack while working on it.

If you do find it is smoke tar, clean it off with the most benign cleaner that will take it off, but do something to protect the chassis afterwards.  Be particularly careful with painted surfaces as they can be harmed by some cleaners, or at least dulled.  

A wipe-down with WD-40 may suffice.  It's better as a protectant than a lubricant as it leaves a bit of a waxy oil residue.  Don't load it on and allow to dry out fully before operating the equipment.


regards,
Barry






-- ~DA~ <iluznst at yahoo.com> wrote:
Hi,

How does one tell if the yellowy colour on a receiver
is a nicotine stain or just old clear coaing of some
sort? No jokes you wisenheimers, :)

Happy holidays,
DA

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