I use aceylene entirely, and 80% of my business is platinum - I have no problems related to gas
I had to learn the hard way about Pt and Acetylene, it was all I had
when I first started and I have some scrap that is really brittle
and does not form well without breaking, but I did have some that
turned out fine and no problems, I was also using a graphite
crucible, (Big No No) but hey that is how you learn with no one to
teach you. But I found that if I used a really heavy oxidizing flame
it would turn out fine, it is a minimal amount that went bad and I
think it is because I did not to that.
That is my take on the whole Oxy/Acetylene thing, it does
contaminate, but you can get it to work too.
Aaron A Tracy