As to closing air vents, it’s all in temperature control. Well let me
qualify that. Wear safety glasses. First: plan your soldering
sequences and IF there is an air vent it is most important that any
liquid must be carefully, slowly heated out.
This is the sequence I follow:
I use only hard and medium solder and try not to get ANY liquid
inside the object through a pre-drilled hole. I will not put the
article in the acid or water.
Now, before I plug the hole with EASY solder I prepare a tapered
wire, melting a large pallion of easy solder on the tip of the
tapered wire held in tweezers.
I warm the whole article up slowly, trying to bring the whole piece
up to near the temperature at which easy solder melts. Then I
concentrate the flame on the hole and bring the tapered wire down
into the hole.
Remove the heat as soon as the solder melts.
Hopefully the solder melts sealing the hole with the wire plug.
Now leave to cool completely before placing in the acid.
When removed from the acid and washed I always heat the article very
carefully watching for any spurts of steam, if there are any spurts
remove the flame, reheat a bit then plunge any hole into bicarbonate
of soda solution. If there is a reaction then there is acid in the
work. Reheat gently till the spurting stops and plunge into water,
reheat till the spurting stops and drill a hole where the spurt was
and solder plug as before.
It is imperative that there is no acid or even liquid trapped in a
piece as it will inevitable leak out and could injure your client.
Have you got product liability insurance?
Advice given sincerely is not necessarily definitive. Usual
disclaimers. Read other posts.