I’ve been quietly observing for some time and would really
appreciate some help. I bought pitch and was told to fill the bowl
partially with plaster and then add pitch.
Okay, I understand the partial fill with plaster. But how do I make
a hunk of pitch (german red) ooze into the bowl. I am thinking cut a
conservative hunk and put it the oven (kitchen) on something like
250 degree F and watch it periodically until it does its thing. Is
this right?
Also, if I want to put some on the end of a 2x4 to also work
with…what is the procedure for that…I don’t really want to mess
up my oven…yikes!
FInd a cheap old soup pot, melt the pitch in there. (GENTLY!!) Then
just pour the liquid pitch into the bowl and let it harden.
(Personally, I don’t use plaster, but large blocks of lead about
half the size of a normal brick.)
The big trick is to keep the heat very low so you don’t burn the
pitch. Also, it’s incredibly important that when you go to re-melt
any that’s left in there for other uses, start with the pot half off
the burner such that one side melts first. Keep the temp low. I heard
of a really horrific accident a few years before me in school where
someone just tossed the pitch pot onto a burner dead center, then
went away for a few minutes. The melted pitch on the bottom expanded
and blew the still solid top off, spraying molten pitch all over the
place. You really want to make sure that one edge of the pot is
molten all the way to the top as a vent before you start working on
the middle. Keep that in mind, and it’s perfectly safe. I’ve been
melting pitch in an old camping pot for years with no problems. (It’s
very much the same concept as drilling a hole in a fully closed
volume before trying to solder on it.) Needless to say, a face shield
is not optional when doing this.
As far as putting it on a 2x4, I’d start with a 2x4 lump, warm it
with a torch, and just stick it to the end of the 2x4. Use a wet
metal spatula to ‘pat’ the pitch into position. You could pour a
puddle out of the pot, then herd it with the spatula, if that seems
easier.
I've been quietly observing for some time and would really
appreciate some help. I bought pitch and was told to fill the bowl
partially with plaster and then add pitch.
Plaster filled pitch bowls are far too light to use properly and
with time the plaster fractures and comes up making a mess in your
nice pitch. You want the bowl as heavy as you can get it. I like to
fill mine with lead, and take very good care not to breathe the
fumes, in a fume hood or equivalent ventilation, Fill it almost full,
a quarter inch below the rim. In Portugal I’ve seen granite balls
used, flat topped like th bowling ball shown on this page at
Ganoksin:
use a hair dryer (or heat gun) to heat the pitch, it is not runny at
all, soft like clay and you can touch it, press it into shape. Let
the heat percolate through slowly, very gently and slowly. Don’t rush
it. If it is glossy and sticks to your skin you are too hot. same
with smoking and bubbling.
I was taught by my jewelry instructor to heat the German wax in a
clean and dry coffee can. Heat with the torch until melted and add
very small increments of olive oil until, when cool, the wax just
very slightly bends between the fingers, then breaks. Use bamboo chop
sticks to stir in the oil well, while continuing to heat. You can
ruin the whole batch if you add too much olive oil. As the mixture is
heated (this whole time), lift the chop sticks up over the coffee can
to make a strand of the wax. Dip the strand in a bowl of cool water.
Test that strand as it cools using the above method. It’s tricky, but
worth it! I suppose you could try a smaller amount, then do the
whole after you know you’ve got the right consistency. This recipe
allows the wax to conform to the “blows” of the tools on the metal,
but will not break the surface of the wax.
Then pour into the pitch bowl or box. Hopefully, you can make a
slight fingernail mark, but not a thumbprint (too much oil) after it
cools and hardens.
Never heard about the plaster. We used enough to fill a 10"X12"X2"
box, plus the pitch bowl. One for large chasing/repousse and one for
smaller jobs.
I have changed from using plaster in the pitch pots to Quickrete.
One of the professors here likes to cool the pitch in running water.
If water gets under the pitch the plaster breaks down and mixes with
the pitch making a mess. I also buy the 6 or 8 inch acorn fence post
tops from Hoover Fence for the pots and lawnmower tires(pop out the
plastic centers) for the pitch pot holder. We use heat guns, the kind
used to remove paint, to soften the pitch. In the summer I just set
the pitch pot out in the sun for some southern exposure.
The first suggestion I would make would be to forget the plaster and
insert a chunk or chunks of wood of a suitable size into your bowl.
Forget the oven also, I’m forty six years working at this trade and
I have never heard of anyone putting pitch in an oven and in the
interests of safety I don’t think its a great idea. All you need is
a stainless steel pot to melt your pitch in at a low heat and then
just pour your melted pitch into the pitch bowl.
I’ve done precious little work with pitch - I AM NOT AN EXPERT - but
this discussion about “preparing pitch bowls” makes me wonder if
someone has not misunderstood or misread some instructions about how
to use pitch. I have read in more than one source advice about how to
prepare the pitch itself (not the pitch bowl). The pitch, straight
off the shelf, doesn’t suit all needs or all styles of work. One
might wish to make it harder or softer according to one’s needs. It
was in that context that I understood that dry plaster powder was
recommended as an additive to make pitch stiffer. One melts the
pitch, stirs in some dry plaster and lets it all set up. Likewise,
for a softer pitch, one would add a bit of oil.
I’m wondering if this is where the idea about putting “Plaster in
the bottom of the bowl” came from - a simple misunderstanding of the
uses of plaster powder in pitch preparation. Whaddya think? Anyway I
agree with the person who said that plaster in the bowl is not a good
idea because (a) the plaster is too light (you want a pitch bowl to
be heavy) and (b) because the plaster might break up and get mixed
into the pitch - making an awful mess. If I were to put anything in
the bottom of the pitch bowl, (presumably this is intended to bulk up
the pitch or raise its level in the bowl without having to buy a lot
of expensive pitch) I might use something heavier and more durable
than plaster - maybe some rocks or steel ball bearings.
No, the “plaster in the bottom of the bowl” thing isn’t a
misunderstanding, it’s a fairly standard trick. The issue is that to
do their jobs correctly, pitchbowls need to be hemispherical. Which
leaves a huge volume in the bottom of the bowl that most people
will never use. Thus the origin of the idea of filling that volume
with something cheaper than pitch…like plaster.
I’ve known people to use concrete, or redi-mix, which is heavier
than plaster. Personally, I use large lead bricks, but that’s because
I have them, and I do a lot of things where I want the bowl to be
pretty massive. (and thus resist moving while I bang on it.) The
reason pitchbowls are hemispherical is so that you can tilt and spin
them to whatever angle you need while you’re working. The reason you
want them heavy is so that they stay at that angle while you pound
on them.
As Charles noted in his comments about pitch bowls, I have found that
the plaster I originally used as a filler in the bottom of my pitch
bowls did eventually crack and break up after heavy use. I have also
changed over to using concrete instead. I use a “quikcrete” product
from the local home and builder’s supply center. It is an easy to mix
fast setting type of cement commonly used for securing fenceposts,
etc. This works well for me and it adds a bit more weight to the bowl
which is helpful.
I have prepared my bowls by putting them in the oven (on an old
cookie sheet) to melt the pitch. This is what Valentin reccomends
and it works well. I set the temperature at 325 degrees (F) for the
red German pitch. It takes 20 to 30 minutes to melt. Just make sure
to turn the oven off and allow the bowl to cool completely before
removing it from the oven. Additional pitch can be built up
afterwards on the top of the bowl by adding pieces and melting with a
heatgun.
The way I was taught how to make the pitch bowl is using an old
bowling ball. You cut it in half, and use the pitch on the cut side
with some type of craddle on the other side. Or you could use the
pitch on the rounded part depending what your working on. That would
certainly give you the weight, and you wouldn’t need lots of pitch to
fill the bowl.
I know that Karl Fischer (www.fischer-pforzheim.de, request a
catalogue) has the red sealing wax and it’s very expensive. But I
purchased mine through my teacher. Must have been about 5 pounds or
so and came as big chunks of red sealing wax. About 4 years ago I
reimbursed him about $30.00. I have heard that it’s more today.
When I talk with him in the next week or two, I’ll ask him about his
source and get back to orchid with a post.
How, and/or with what, do you cut a bowling ball in half? I've got
That’s a good question. I know we covered pitch bowls in a simpler
fashion that I will share which some may find useful.
Get a dirt chep metal mixing bowl.
On your sand bag or what have you with a rounded out stick or how
ever else you wish to do it, pound out the bottom to make it rounded.
Get some scrap pieces of steel, be it large nuts or bolts. I had a
thick rod I wasn’t going to be using any time soon so I choped that
up and filled the bowl a third full.
I went to the hardware store and picked up an spare Bar-b-cue
wheel and peel off the tire to use as my pitch bowl base.
From a second hand store I found a crock pot so I ground off the
keyed lip, but if you find just a cooking pot then you’re good.
On a dedicated heating element at medium heat in a well ventilated
room (I maybe should have done this outside) I brought tar to a
liquid consistensy… I broke off chunks from a larger piece using a
scrap piece of sheet steel and a five pound sledge.
Slowly I added Plaster of Paris, mixing/stiring it with a stick
until the pitch turned to a velvety plastic looking mixture. It took
a surprisingly large quantity, maybe 4 cups for a 3/4 full pot.
Fill the bowl like it was pudding.
Have a torcb about to heat the surface while it cool as you want
to work out any bubbles that rise so the surface is nice and flat and
doesn’t have any air pockets.
Note: Don’t catch you pitch on fire or it will become brittle and
loose the properties you need it for. Melt, skim off, heat surface to
make it flat and work out air pockets.
How, and/or with what, do you cut a bowling ball in half? I've got
two, yard sale bowling balls, in storage, so that part is easy...
Bowling balls ar made of a hard rubber or a plastic material
depending on the age of the ball. Both materials are easily cut with
with a carpenters hand saw.
It’s probably a two person job, unless you’ve got a big vise, one
person to hold the ball still & the other to saw. If you’re fortunate
enough to have a large band saw, or know someone who does, that may
also work.
I have read every thread in the archives on pitch bowls and pitch. My
husband bought me a beautiful German 8" bowl and pitch from Otto Frei
for my birthday, and I am ready to prepare it. I am confused on a few
things and need some assistance. My questions are as follows: If I
fill my bowl with quikcrete - do I just follow package directions on
mixing it up? What is the correct consistency? Should I let it set
for 24-48 hours like plaster of paris? Do I fill the bowl and leave
3"or 2" from the top for the pitch? Does it matter? Once I crack the
pitch and put it into the bowl on top of the quikcrete and put that
into a 350 degree oven, do I have to worry that the quikcrete will
crack from the heat of the oven underneath the pitch? Does it matter?
How do you know how much pitch is needed once you fill it partially
with quikcrete? Do you watch it and add more as it is heating in the
oven? Or do I just put it all in - because that is the correct amount
in that metal pan? I did read that I could add more with a heat gun
after the bowl was cool, but how much can you add with a heat gun? Is
it best to underfill the bowl and then use the heat gun to be safe?
Sorry for so many questions…