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Hot plates - Keum Boo


#1

I am looking for a hot plate for Keum Boo. I would like one with a
solid top, but most of the inexpensive ones have spiral elements. A
typical one has a single element, 1100 Watts and variable control. I
found one that has 1500 Watts and solid top, but is around $100.
Question: is it really worth trying to find one with a solid top?
Or, could I just put a piece of cast iron or somesuch on top? Is
there much advantage to the higher wattage level?

Another question: would there be any advantage to using this for
other soldering jobs where even heat distribution is critical? It
seems that a hotplate could be used to solder on top of, in order to
reduce temurature variation in the piece being soldered. Just an
idea.

Todd Welti
Research Acoustician
Harman International Industries
Northridge, CA
(818) 895 8124
@Todd_Welti
TWelti@harman.com


#2

I do a lot of Keum Boo, and found that the hot plate with a calrod
(spiral) element is perfect. Mine cost around $30.00 at the local
housewares department of our hardware store. Single element,
variable control, nothing fancy.

I also have a solid top one, but much prefer the spiral element, as I
can nestle rounded objects between the coils and they don’t become
flattened, nor do they swivel around.

As far as heat—I set it for maximum temp, and achieve better
adhesion of the gold to the silver.

You ask about using it for soldering. I have never tried that, but it
is an interesting idea. I have used it to anneal 24K gold when I have
been running it through the rolling mill to get it thin enough for
the keum boo. I just put the work hardened gold on the plate until it
sort of sags.

(yes–24K gold does get work hardened—same as fine silver).

Alma


#3

I use a cheapo single “spiral element”-type and put a piece of 18ga
brass that I had laying around the shop on top of it. Yesterday, I
misplaced the brass and used the screen off the tripod I never use
and it worked just fine too.


#4
       is it really worth trying to find one with a solid top? Or,
could I just put a piece of cast iron or somesuch on top? 

You can use any fairly thick, heavy piece of metal that will hold up
to heat. A bench block, a piece of steel plate, copper plate,
aluminum plate. Ideally, the plate will cover the element entirely.
It can even be done on top of a gas range.

       would there be any advantage to using this for other
soldering jobs where even heat distribution is critical? 

Well, you could, but you might have a little problem with the heat
rising from under the plate. If you’re not careful, you can melt
your hoses. A lot of people wear gloves when doing keum-boo to
prevent getting toasty fingers, and that’s with having lots of
nerves telling you things are getting too hot. A better choice will
be a firebrick or a trinket (tabletop) kiln for this purpose.

 has anyone tried using any of the oxidizing solutions used to
patinate silver for the oxidation part? 

Yes, typical liver-of-sulfur solutions are used most often. The gold
isn’t very reactive if no steel is introduced, and stays bright, or
can easily be polished with a light touch. You can look at some of
my pieces in the Orchid Gallery.

http://www.ganoksin.com/orchid/palo.htm

I think there are a few other artists there with patinated keum-boo.

Katherine Palochak


#5

Hot plates are on sale now – where did I just see that? Maybe
K-mart.

No, it’s not worth $100.00 for a solid top. Celie Fago recommends
putting a piece of 18 g brass on top of the coil, which I do, and it
works great.

You cand find a single burner hot plate at discount stores - K-mart,
Wal-Mart, etc. They are $19.99 at K-mart, unless on sale. 9.99 at
Wal-Mart, but the one I got there broke rather quickly.

You can find a more expensive double burner one – about $30.00 at
Target. All are exposed coil.

For soldering jobs – some people use the JEC Ultralight Beehive kiln
for granulation – it can also be used to fuse jump rings.

Elaine
Elaine Luther
Metalsmith, Certified PMC Instructor
http://www.CreativeTextureTools.com
Hard to Find Tools for Metal Clay


#6

Hi Todd, Yes you should try to find a solid top. I bought mine at
Wal-Mart. Any of those types of stores should supply hotplates. If
not then you an always place a sheet of heavy gauge red brass copper
on the top. Bend to fit the burners and wha la!!!

Helen


#7

hello Todd Welti—

I saw your inquiry about expensive solid top versus cheap coil top
hot plates. I have used both and I actually prefer the cheap coil top
hot plates. I believe I bought mine at Wal-Mart several years back
for under us$10.

The solid top ones have a down fall when you want to lay an earring
flat on them with the ear posts attached. I complete all my
fabrication prior to application of the gold foil so then I often
have posts and projections sticking off of them varying with each
design.

I have and old sheet of 18gague/1mm brass that can really be of any
size, mine is about 5x5 inches. I lay this over the coil top; it
converts it to a flat top and is a reasonable effective converter of
heat. I have drilled a couple of tiny 1mm holes in it. I can lay the
earring flat on the brass sheet with the ear post poking through the
hole. The earring sits flat on the sheet and soaks up the heat
rapidly.

Initially I had a problem with the earring pivoting around as I
tried to burnish them and easily solved this by soldering an old
screw to my brass sheet sticking up so the work piece would not spin
around as I try to burnish it. I frees up one hand. I’ve even dapped
a portion on my brass sheet to accommodate a particular design. I
don’t remember the wattage of my plate but it fast it gets plenty
hot for keum boo.

As to your other questions about patinas. Yes liver of sulfur will
darken depletion gilded sterling quite effectively. I like the
sharp contrast and most of my keum boo work is black and gold. In
fact often when I don’t feel like depletion gilding sterling silver I
just use plain old fine silver and it works well. I don’t know why
chemically but fine silver takes a good rich dark black patina with
liver of sulfur; as I had thought the los was working on the copper
in the sterling. I use the same hot plate to heat up my liver of
sulfur solution in a cut off beer can. It is very easy to determine
if one have a good bond or not. As I’m sure you know clean is
important to keum boo but I don’t do all the meticulous scrubbing
and cleaning that all the books mention. I start off with materials
that are fairly clean to begin with and I seem to get by just fine
with a 15 minute soak in some hot pickle rinsed with water then right
before I put each piece on the hot plate I give them a quick dip on
some strong 90% isopropyl alcohol and handle them by the edges; by
then I’m usually wearing a glove on one hand anyway.

Good luck.

Have Fun. If you have any further questions just holler.

Mark Kaplan
providence, rhode island usa
soon to be moving to rome, italy
looking to connect with folks over there.