Some suggestions re: platinum work.
#1. You must use dark lens eye protection. No. 5 shade (in the US)
is quite common. Some people can go a bit less dark but not much
less. For melting platinum you need to go darker. The lens needs to
be glass, not plastic. Don’t use dark sun glasses!
#2. 18 gauge wire is easy to solder or melt using the correct flame.
Oxy / propane is fine as far as heat production if the flame is
correctly adjusted. For propane you need a Multi-Port Tip, not a
single hole “needle” Tip. Multi-Port Tips like produced by Paige
Tools. (sorry for the plug. Paige does not produce Tips for the
Swiss Torch though). Single hole Tips, regular or needle style are
for acetylene or hydrogen, not propane or natural gas. Gas pressure
is not as much an issue as setting the correct flame profile. For
platinum work you want an oxidizing flame profile. Less fuel gas
with excess oxygen. The correct flame will have a very sharp, inner
cone that’s almost white color. The more oxidizing the flame gets
the louder the flame sound or hiss. Platinum will get white hot
before melting and only a little less intense white in soldering.
The tip of the inner cone goes right on the metal, not slightly away
as in gold or silver work. Single hole Tips can also be adjusted to
oxidizing flames but the flames are not stable and are much harder
#3. If you use the correct, Multi-Port Tip and adjust it to a hard,
oxidizing flame soldering or balling up the end of 18 gauge platinum
wire is easy. You do not need a large (gas) volume Tip for the wire
size you indicated. The 5 psi of propane is fine but you need double
that psi of oxygen. Gas pressures depend a lot on Tip styles and
sizes. I can’t stress enough how much easier Torch work is using the
correct style Tip that’s matched to the fuel gas used.
#4. You might consider saving a few dollars and trying different
buffing / polishing materials. Try using a “bobbing” compound before
going to common Tripoli. There are also various platinum tripoli
compounds which work well. Brand is not too important. Even regular
tripoli does pretty well so platinum tripoli is not always needed.
Platinum rouge is almost a must. I use the green color platinum
rouge followed by red rouge. There are other compound options as
well. Stitched cotton buffs work O. K., stitched leather works
better and is what I’d use for the final polishing stages. Always a
different buff with each compound and only used for platinum work.
In summary: Do not neglect eye protection. You’re working with white
hot metal and correct shade protection is a must! If you use propane
(or natural gas) you need a Multi-Port Tip. Adjust the flame to a
hard oxidizing profile and put the tip of the central cone right on
the joint or wire end.