Richard,
1.I don't believe that dynamo armatures need to be vacuum impregnated with varnish, in fact, I had never heard of such a thing in my apprentice days.
The bloke that I know who is rewinding magnetos does, however, vacuum varnish his armatures. Probably a good idea as magy windings are much more tightly packed than dynamo ones.
I dip the armature in the varnish until the air bubbles stop and then do the cooking.
2. The varnish is a special insulating product. I am using the last known tin of Hymeg that I know of.
I also have Isopron [clear] which the manufacturers say is an air drying type and should not be baked but I bake it anyhow with no problems.
3. The temperature required is 135F.
4. There is no place on earth to which you could send your wife while you cook an armature in the house! Divorce is the best option. This also applies to crankcases, bearings etc but the varnish is worse.
I have an old stove in the shed which is used for all of these tasks but every time the oven is heated all that can be smelt is varnish.
My wife won't enter the shed while ever the oven is heating. Maybe this is a good thing but I make sure that the oven is cold come beer o'clock!
Trev.
