charleygold, Coating the inside of a canteen with beeswax isn't a difficult process.
There are a host of potential mishaps associated with heating beeswax & pouring the hot liquid into the canteen.
It is safer & effective to melt the beeswax inside the canteen. Unscented beeswax candles of the correct diameter are an ideal source. Just break a candle up to remove the wick. Alternatively, beeswax is not difficult to cut up into proper sized chunks using a knife dipped in boiling water.
Preheat oven to 200 degrees F.
Put the wax into the canteen.
Place the stoppered canteen onto a cookie sheet for easy handling.
Place in oven for (+/-) 15 minutes.
You don't want to over heat the canteen & pop the cork out.
Beeswax melts at 144 -164 F / 62 - 64 C.
Use a towel to wrap around the canteen. Be sure to cover the cork in case it pops out. All you do is roll it around to coat the inside. Gently shake it until you can't hear liquid.
Pull out the stopper & let it cool. If you don't take out the stopper as the wax cools a partial vacuum will form & removing the stopper will be challenging.
I found a UTube demo by Arch (?) that shows how he does the oven heating method. Be sure to put the towel over the stopper. You don't want to have it pop out & throw hot wax everywhere! He uses a cork, I have just used the regular stopper. See more here.
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