[Milsurplus] MFP Varnish Experiment

[J Forster]

Terrific work !!  Thanks very much. What's the URL of the chemical supplier,
please.

-John



Tom Dawson wrote:

> Back in mid September or so some of the chaps here were discussing MFP
> varnish, whether is was very toxic and what solvents wee appropriate for
> removing it.
>
> This got me thinking as to how tough it would be to reproduce a suitable
> varnish from "purchasable" stuff.
>
> The MIL Spec referred to, MIL-V-173, specifies a tung oil, phenolic varnish.
> This sort of  varnish is much less common today than urethane spar varnish,
> but I was able to find a product, "Waterlox Original" Marine Finish which is
> a available online for about 33 bucks per quart that seemed to fill the
> bill.  You can get it from Wood Carvers Supply Stores from
> www.woodworker.com .
>
> By itself, the varnish looks OK although not quite yellow enough to pass for
> the real thing.  Still, better than nothing.
>
> MIL-V-173 calls out oxine copper as the fungicide.  I don't know for certain
> that this was the fungicide in the 40's but it looks to have been used in
> the 60's.  I've seen copper sulphate solutions used for hoof-fungus (Thrush)
> in horses, so a copper based fungicide makes sense.
>
> There are all kinds of different trade names for this substance but I found
> a source for 8-Hydroxyquinoline, copper (ii) salt at one chemical supplier
> (57 bucks for 5 grams) and bit the bullet to see how it would work.
>
> Mixed up 1 gram of the copper salt with 100 grams of the vanish, by weight,
> because the spec called for 1% oxine copper.  100 grams of the varnish just
> about fills up a small baby-food jar.
>
> Turns out to be pretty close to the color of the varnish on an old RA-20
> that's been around here for 10 years or so.
>
> Given the prices of the varnish and the fungicide, this comes to about 18
> bucks for 100 grams of home-brew MFP.  If the oxine copper doesn't make you
> choke, the price just might.  The 80 bucks/quart does not sound so bad.
>
> The fungicide is not a hazmat, but you need to keep it out of the surface
> and ground water as it is very toxic to fish.  Also, it is very irritating
> to your lungs so you want to be sure not to inhale any of it.  (This
> presumes that you're crazy enough to try this at home after hearing the
> prices).
>
> The varnish is pretty thick, so if you want to spray it (use a mask) it
> looks like mineral spirits is the stuff, or maybe xylene.  Mineral spirits
> is first on the list of ingredients, and xylene is last.
>
> At any rate, it was a diverting experiment and I now have a hundred grams of
> a fairly authentic MFP varnish that actually contains a fungicide, and is
> not overly dangerous to work with.  If you're not planning on demonstrating
> your Military Radios in the tropics, the Waterlox ought to be adequate by
> itself, even if it is a little paler than the mix with fungicide.
>
> Happy Holidays.
>
> Tom
> WB3AKD