I am making a propane forge, and could only get some parts in galvanized. Small amounts of zinc being heated and burnt off I find reasonable (electroplated fasteners), but I want to avoid large exposure to zinc, even though it is a necessary nutrient and eliminated from the body reasonably well for a metal, it can quickly build up to toxic levels. I grind away zinc at least 1/2 inch back from any welds on galvanized sheet metal, avoid heating of hot-dip galvanized, solid zinc or die-cast parts, etc.
It was recommended by several people to use vinegar or muriatic acid to strip the zinc off. I decided to use white vinegar as I had some. I put my parts in a Ziploc bag with about a quart of vinegar. Overnight the bag inflated and split at the bottom, but the parts remained covered with vinegar. I removed and rinsed the parts, but was very surprised that half the zinc remained. This brings up the first question: How long and how much vinegar is needed to strip say a 2 inch diameter x 8 inch galvanized pipe? Yes, I know thickness of zinc varies from part to part, even in the same batch.
I cut up a rinsed out apple juice jug to make a bucket, put my parts in with fresh vinegar and put it in the corner, figuring I would not mess with them today. About 5 minutes later I had to get something out of the garage, and started coughing uncontrollably as soon as I walked in. I opened the garage door and moved the jug outside. It took about 10 minutes sitting outside to feel normal again.
My chemistry is very rusty, and the msds for distilled white vinegar (acetic acid 5%) and hydrogen gas seem to be not helpful. Vinegar vapor is listed as an irritant, but does not make me cough like that. I use it to clean with on a regular basis with little ventilation. Hydrogen gas is an odorless, tasteless, non-irritating, flammable, suffocation hazard. My second question is: Why is dissolving zinc with vinegar so vile? Is there a different, possibly toxic, gaseous product produced besides hydrogen?
Lastly, is muriatic acid significantly quicker at dissolving zinc? I mean minutes instead of hours or days. Will less be needed? Short soak time is very desirable when working outside without a roof available. Right now it is raining in my jug of vinegar and parts. Cost for a gallon of white vinegar is just a couple of dollars at the grocery store while a gallon of muriatic acid is $20-$30 last I checked. If volume of acid needed is similar, then I can wait a few days to remove the zinc, with my jug outside.
Thanks in advance for any insight
Phil
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