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Hydrogen Questions


#1

Hi Everyone, I just switched from Acetylene/Oxy to Hydrogen/Oxy. I’m
used to the high heat of acy. so thats no problem but since the hyd.
flame is invisible I am perplexed as to how to set my blend on my
torch consistantly. I dont have a problem soldering with an
invisible flame once the oxy/hyd blend is right since the metal
appears to behave the same as with acetylene but it seems like I
cant get the mix the same each time and I have heat inconsistancies.
How does everyone else do it? Sure not missing the sooty mess!
Second question…Is there any special considerations when casting
with acetylene? I cast alot of 18kpd white gold and have been
advised that my acetylene is not the best gas for this metal, hence
the switch.

t lee


#2

Hi T.Lee, I have used Hydrogen in the past, however, I found it to be
very expensive to use for casting purposes and I also found that it
was very easy to overheat small batches of metal… hence, I stopped
using this and have been using Oxy -Propane for over 10 years… A
$20 tank of propane lasts me about 2 weeks of casting 20-30 large
flasks /day. It is very easy to control, has good visibility and No
Soot :slight_smile: We melt batches of metal from 20 grams to 1 kilo… (2 .2
Lbs) best Wishes,

Daniel Grandi

We do casting,finishing,in gold,silver ,bronze/brass and pewter as
well as assembly , model work for our customers , molds and a whole
lot more. Contact : sales@racecarjewelry.com


#3
 Is there any special considerations when casting with acetylene? 
I cast alot of 18kpd white gold and have been advised that my
acetylene is not the best gas for this metal, hence the switch. 

I assume you meant are there considerations when casting with
hydrogen… If you’re using nickel white golds, be sure your flame is
not too too soft and reducing. Too much free hydrogen can lead to
the nickle absorbing hydrogen (just like fine silver absorbs oxygen).
It then comes out of solution on cooling, resulting in problematic
porosity. Hydrogen is great for casting or working platinum, but at
least in my opinion, perhaps not the best for casting golds, at least
those with nickle or substantial copper (which also absorbs/dissolves
hydrogen when molten) in the alloys. I prefer casting with either
natural gas or propane as fuels. Also as far as setting the flame,
you might check out installing a vapor fluxing unit on the gas
supply. These are standard additions to the “water torches”, and
amount to some method of bubbling the gas through a flux mix, which
can be, for example, acetone with boric acid, or other such. It not
only lowers the flame temp a bit, which is nice so you don’t totally
burn the metal with that high temp, but it also makes it much more
visible. and it’s then self fluxing too. Without that, setting a
neutral flame can be helped by dusting a bit of boric acid or borax
on the end of the torch tip, which causes a sodium flare in the
flame, also making it more visible. And there’s also always the
sound of the flame. As with other fuels, the sound changes when it
gets oxidizing. Also, if the lights are dimmed enough, the flame
isn’t really invisible. Just pale. You can, with dimmer lighting,
see the flame structure, at which point you set the flame
characteristics the same as with other fuels.

Hope that helps.
Peter Rowe


#4
 since the hyd. flame is invisible I am perplexed as to how to set
my blend on my torch consistantly. 

First, If you are using a “flux” in your torch system such as MEK or
Methyl Alcohol dissolve some borax in the liquid. This will then
turn your flame a greenish color so you can see it.

If you don’t have a chamber for the “flux” solution then you will
need one. They are not easy to make since they have several chambers
in side and are completely sealed. They can be purchased but I don’t
have a price for you right now.

I suspect your differing heat problem is because your flame size is
different not because the hydrogen mixture is different.

If you have any other questions contact me and I can help solve your
problems.

Ken Kotoski
MPG Repair
www.mpgrepair.com
1-877-262-2185