What can I use to remove oxidation (caused by a propane/o2 torch)
from titanium sheet? I enamel copper and silver using a torch. I put
my workpiece (with enamel powder on both sides) onto titanium sheet
and fire with a torch from the underside of the titanium. This works
great as a method of torch enameling (the hot enamel doesn’t stick
to clean titanium), but leaves me with oxidation/firescale on the
titanium sheet afterwards. If I don’t remove the oxidation, the
enamel sticks to the titanium. Sparex pickle doesn’t work. I’ve been
grinding it off, but would rather use a pickle if there is one that
will work.
I would think you are seeing pretty heavy oxidation. While MultiEtch
will attack and remove light oxidation… meaning the pretty colors,
what you have is something else. I would imagine it looks more
ceramic like after prolonged heating. Commercially it could/would be
removed with nitric/hf acid bath. Way to dangerous for casual use.
This is tuff stuff. I think you are stuck with grinding.
I would suggest MultiEtch from Reactive Metals but. I am not certain
it is available in the UK and I believe you are in the UK ? You
might look for glass etching cream which will have a fluoride salt in
it and that will clean the Ti. Strong concentrations of reagent grade
hydrochloric or sulfuric acid may also possibly work you will need
lots of ventilation and health and safety gear are appropriate. The
sure fire method is hydrofluoric acid but it is incredibly dangerous
to handle so should only be used with proper training and
appropriate health and safety equipment. A spill of hydrofluoric acid
covering an area the size of a playing card on your skin will most
likely kill you and if not will certainly put you in the hospital for
a while.
So if you cannot find MultiEtch or a glass etching cream I would say
the safest thing is to keep sanding it off.
If I don't remove the oxidation, the enamel sticks to the titanium.
That’s a puzzling statement, Jamie. The reason is that while you can
grind or etch off the deeper colored oxide layers from titanium, you
don’t end up with an oxide free surface. Titanium is a reactive
metal. That means that on contact with oxygen, even at room temps, it
forms an oxide layer automatically. Normally, without heat, that
layer is thin and colorless. The colors upon heating are merely
because the layer gets thicker and becomes optically active with
interference colors. But it’s the same type of oxide, as far as I
know. So it’s puzzling that enamel would stick to that deeper oxide,
but not to the thinner oxide layer on clean titanium…
As to removing it, try Multi etch from Reactive Metals inc. Safer
than hydrofluoric acid by far. But remember, as soon as it’s dry and
open to the air, it quickly again forms that thin impervious oxide
layer again…
Peter, I think he is seeing much thicker oxides then the angstrom
thick color generating sort. Heating for extended times at high heat
is going to produce porous Ti oxides like my hot spun pieces. Indeed
stuff will soak in and stick to it.
I think he is seeing much thicker oxides then the angstrom thick
color generating sort. Heating for extended times at high heat is
going to produce porous Ti oxides like my hot spun pieces. Indeed
stuff will soak in and stick to it.
This is exactly correct. Someone mentioned that your MultiEtch will
take care of this problem. Is this what you’d recommend?
You can try to paint the titanium with iodine next time before you
fire.
Have you tried this? Or what is the basis of your recommendation.
I’m willing to try it, but don’t have any iodine. I’ll buy some if
there’s a reasonable chance of success.
Thanks for your idea for using MultiEtch. Also, thanks for the link
to your web site. Your flashlights are the coolest! I especially
like the Mokume-Gane. http://photonfanatic.com I recommend others to
check it out.
I would think you are seeing pretty heavy oxidation. While
MultiEtch will attack and remove light oxidation... meaning the
pretty colors, what you have is something else. I would imagine it
looks more ceramic like after prolonged heating. Commercially it
could/would be removed with nitric/hf acid bath. Way to dangerous
for casual use. This is tuff stuff. I think you are stuck with
grinding.
I didn’t see your response before I asked the question about
MultiEtch. Please excuse my cart before the horse. Thanks for the
info. And yes, the oxidation is well beyond the pretty colors. Since
I’m not wild about setting up to properly handle unaccustomed
chemicals, I will stick with grinding.
Jamie, I never did this with titanium, but I paint iodine on copper
sheet which I use as a base for plique a jour. The enamel will not
stick to the copper. Much cleaner than mica. No hassle. You can get
the stuff at any pharmacy. A 10 to 15 % iodine solution works fine -
the rest will be ethanol. Warm the metal up just a bit, otherwise
it won’t stick, then paint it on.
That ceramic like oxide is very dificult to remove chemicaly however
it responds to grit blasting quite nicely. The oxide is brittle and
just disintigrates when useing 100 grit aluminum oxide in a sand
blasting cabinet.