[Milsurplus] Water, Water Everywhere.

[Bob Camp]

Hi


> On Dec 11, 2015, at 7:50 PM, John Hutchins <jphutch60bj at gmail.com> wrote:
> 
> David/Bob - All-
>  The dry out box could be made from HVAC fiber glass board and aluminum Tape with  heat lamp.
> If you could get the lamp on the bottom and have and  oven rack to let the heat circulate.  you may be able to get an oven rack from a used /junk appliance store.  The fiberglass Board from Homedepot?
> 
> As you say meed to seal the Bakelite how about a couple coats of varnish?

If you have a good two part urethane varnish (mil spec conformal coat), you can do a pretty good job. 
I suspect that if you have some of that in stock, you don’t need the info in this thread … Normal varnish
is all over the place in terms of penetration and humidity protection. To some extent it’s a “you get what
you pay for” deal. Some of what you are buying is better resistance to UV damage. 

Bob

> 
> My Thoughts
> Hutch
> 
> On 12/11/2015 11:06 AM, Bob Camp wrote:
>> Hi
>> 
>> Before you start, consider that there may be a layer of dirt involved in the process.
>> The time to get rid of that is *before* the dry out. The usual cautions apply to using
>> solvents to do this.
>> 
>> Winter is a good time to do a dry out process. All you really need to do is
>> get the humidity down low and keep it there for quite a while. You can accelerate
>> things with a lot of heat. That may or may not damage other stuff in the gear. More
>> or less:
>> 
>> Rig a hot box, heat it with what ever you have
>> Monitor the temperature with something simple
>> Keep some air flowing inside the box with a small fan
>> Control the air exchange with the outside so there is *some* exchange
>> For added fun monitor the humidity. (or look at the humidity outdoors and
>> do the delta T math).
>> 
>> The goal would be 0% RH (which is impossible). Anything below 5% is likely to be
>> “good enough"
>> 
>> Once you get the humidity out, you need to keep it from getting back in. The issue
>> is that whatever was doing that probably has degraded in the last 50 to 100 years (haven’t we
>> all …). There are an enormous number of candidates for this. Many of them can create
>> as much trouble as they fix. For solid parts, low viscosity / long setting time epoxy
>> might be your best bet. For delicate little stuff, something like silicon (synthetic) oil
>> may be about the only viable approach. As always, proceed carefully. You very much
>> do *not* want to toss this stuff in there and find it dissolves the part(s). There have been
>> so many materials used over the years that there is no 100% safe thing to use. If oil
>> and epoxy are out, then stuff like wax is your next choice. In a hot part of a radio, they may not
>> do really well. In a room temperature part of the gear, they work quite well.
>> 
>> It’s also quite acceptable to skip the displacement step. You may find that your dry out
>> process needs to be repeated in a few years.
>> 
>> Bob
>> 
>> 
>>> On Dec 11, 2015, at 11:43 AM, David Stinson <arc5 at ix.netcom.com> wrote:
>>> 
>>> Many of our beloved old radios have been sitting, cold
>>> and quiet for many decades.  Some of them getting close to a century.
>>> Recently, I've been dealing with bakelite and phenolic
>>> in our sets which have taken-up moisture over the years.  Right now on the bench I have a TCS
>>> receiver in which one of the pins of Z202, an IF transformer, is leaking B+ to ground through
>>> the phenolic.  Pulling an IF from a TCS is a pain
>>> but do-able.  So may we discuss ways to gently drive moisture
>>> from our sets?  I can "get rough" in the stove with
>>> those bakelite inserts in WWII radio connectors but
>>> that won't do for a whole set.  I've tried powering just the filaments and leaving a set for a couple of days but I don't think they get hot enough to do much
>>> good.  Heat lamps can do some damage.
>>> What have you done?    I'm thinking of light bulbs
>>> with the radio in a thick cardboard box, *outside* in case the box decides to catch fire or something.
>>> 
>>> 73 Dave AB5S
>>> 
>>> 
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