I cannot imagine who would make such a statement regarding the
Ferris File a Wax, unless it was a rep selling a competitive brand
wax.
Or perhaps someone with considerably experience with different wax
types.
I don’t thing one should say the Ferris (or other similar waxes)
file-a-wax type waxes necessarily cause problems, but they ARE
different from injection waxes in the temperature they melt at, and
their behavior during burnout. With injection waxes, burnouts can be
done in less time, sometimes, due to the greater ease in eliminating
the bulk of the wax from the mold. You can ramp up the temperature
more quickly, with less dwell time in the under 500 degree temp
range, without problems. And if you’re careful to properly follow
investing instructions from the investment manufacturers, you’ll also
not likely have problems.
But I promise you, carving waxes CAN cause problems in burnout, if
you cut corners, sometimes in situations where you’d get away with
the shortcut with injection waxes. If your investment is mixed in a
manner which tends to produce a weaker investment, and you heat too
rapidly, then you can sometimes get rougher surfaces than you’d
expect. It’s not an always sort of thing. But the carving waxes are
less forgiving of improper technique in burnout.
Obviously, they’re made for casting, and with proper handling and
technique, they can produce castings of the very highest quality
possible, and most casters, even those without a lot of experience,
don’t have too much trouble properly burning out these waxes, simply
because all you really have to do is follow published investing and
burnout methods reasonably closely. Most of the time I’ve seen
problems with carving waxes, it was when someone, usually someone
with a good deal of experience as a caster, bent the rules a bit too
much. I’ve seen clear cases with flasks that had both types of models
in them, where the injection waxes produced fine surfaced castings,
but the carving waxes were quite noticeably rougher than they should
have been. And in pretty much all those cases, we knew with
reasonable certainty what limit we’d exceeded that was at fault.
Often it was being in too much of a rush, putting the flasks in the
kiln after less than an hour after investing, and running the temp
right up to full burnout temperature just slowly enough so we’d be
sure the investment wouldn’t crack from too rapid heating. Do that
with carving waxes, and sometimes you’ll simply not get away with
your impatience. It’s not always obvious, since in a flask with only
carved waxes, you might not see the surface roughness as an obvious
consequence, if it isn’t so bad. But it’s clear enough when you’ve
got a flask with both types of wax.
I think it’s fair to say, though, that such problems aren’t really
the fault of the wax, but rather the fault of the caster not taking
the wax type into consideration.
By the way, that type of surface roughness can also be caused by
things other than the wax. When I first became involved with
platinum casting, we were plagued with problems with really rough and
deteriorated surfaces on some models. it seemed random, and was
driving us nuts. In the end, though, it turned out that those were
waxes which had been smoothed with those orange oil based wax
polishing agents. These all tend to mention on the bottle that they
don’t contaminate investment. Don’t be so sure. In our case, it
was most apparent on waxes that had been so treated relatively soon
before being invested. The longer the stuff had to dry and
evaporate, the less it affected the castings, but several days were
needed to really dry it, and actually washing it off with water was
better still. But i remember well a test flask we ran with a bunch
of injection waxes. half the tree was “polished” with the wax polish
products, the other not, and it was done soon enough before
investing that the waxes only barely had time enough to appear dry.
So it was a pretty extreme contrast. The castings without the wax
wash were just fine and smooth as desired. The ones with the almost
wet wax polish were so rough and pitted as to be unusable,
Apparently there was some reaction with the polish residue that
inhibited the binders in the platinum investment at the surface, so
the surface just spalled and crumbled when the metal hit it.
Peter Rowe,