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Magnesia soldering block


#1

The mention of magnesia soldering blocks rewminds me of something
I’ve been meaning to ask. A while ago, a friend gave me a mag block.
I tried it, and it seemed to burn and give off fumes where I
soldered on it, so I haven’t touched it since. Is this how magnesia
blocks are supposed to behave? Noel


#2

Hi Noel,

I’ve used several magnesia bricks to the point of extinction & have
never had one that burned & gave off fumes. The only time any smoke
or fumes came off any of mine, it was after something was spilled on
them. Usually what I did then was to remove whatever I was working on
so there was just a bare brick. Then with the biggest tip I had, I’d
burn the spot out. The gunk would be gone, but the brick would be
intact. The brick gets red hot where the torch is being applied.

Dave


#3

Noel, I have had the same experiences with magnesium blocks. They
stink and melt. What type of mag block are you using, Dave? Ryan


#4

Hi Ryan,

What type of mag block are you using, Dave?

To be real honest, I don’t know the exact chemical makeup of the
bricks. I get them at a local brickyard. There, they’re called
’silversmiths bricks’. They’re 2 1/2" x 4 1/2" x 9" & weigh 1# 14 oz.
They’re soft enough that pins can be pushed in with your fingers.
While they’re smooth, they have many holes that may be the result of
small air bubbles trapped when the bricks were cast.

The cost, the last time I bought any was around $4 if I remember
right.

Dave


#5

Hi Dave et al,

I get them at a local brickyard. There, they're called
'silversmiths bricks'. They're 2 1/2" x 4 1/2" x 9" & weigh 1# 14
oz. They're soft enough that pins can be pushed in with your
fingers. While they're smooth, they have many holes that may be the
result of small air bubbles trapped when the bricks were cast. 

I’ve been buying “magnesia” blocks from various suppliers for years
and over the years, the composition has changed so that they’re no
longer as soft as they were at one time. For the kind of soldering I
do most often, I need to be able to push bezel cups into the block so
that I can solder from the back.

A few years ago, when I noticed that the (seemingly the same) blocks
had become too hard to push bezels into, I did a lot of research and
discovered that there is just one manufacturer of all the "magnesia"
blocks sold by jewelry equipment suppliers and that I was therefore
out of luck trying to order the older, softer ones.

Since then, I have tried every other soldering substance shown in
every catalog I can get my hands on, and some that are not even shown
in catalogs. I’ve found a few substances that come close but there’s
something wrong with each one. If I hadn’t casually thrown out
partially-used blocks many years ago, I’d probably have a life-time
supply but, as it is, I have only about 4 of the old blocks left and
eventually I’ll have sanded the surfaces down so much that they’ll
fall apart.

It sounds as if, perhaps (crossing all her fingers), you have found
something different, Dave, and I would love to try it. I’m out of
town at the moment and will check brickyards when I get back to LA
but I have a feeling this isn’t a common item for brickyards to
stock. If you can give me any additional that may help
me locate these blocks or the manufacturer, I would be most grateful.
And if anyone else has another suggestion, I would love to hear it.
(I should note that using investment to stabilize parts is
impractical for my purposes.)

Beth (with only 2 days left in Australia before the 15 hour flight
back home )


#6

Hi Beth & All

It sounds as if, perhaps (crossing all her fingers), you have
found something different, Dave, and I would love to try it.  I'm
out of town at the moment and will check brickyards when I get back
to LA but I have a feeling this isn't a common item for brickyards
to stock.  If you can give me any additional that may
help me locate these blocks or the manufacturer, I would be most
grateful. 

I stopped at the brickyard today to check out the magnesia
firebricks.

Here’s what I found.

The brick I use is the lightweight magnesia fire brick. The brick is
cream colored & is 2 1/2" x 4 1/2" x 9" & weighs 1 lb 14 oz. The
surface was pock marked with small holes probably caused by minute
air bubbles left from the casting process. The cost where I got mine
was $3.45.

According to the folks at the brickyard, they get these bricks
from:

Thermal Ceramics
2102 Old Savannah Rd
PO Box 923
Augusta GA 30903
706-796-4200
www.thermalceramics.com
email: tceramics@thermalceramics.com

I bought a new brick to compare it with the ones I’ve had for some
time. The new brick looked just like the older ones (only cleaner). I
lighted a Prestolite torch with a # 3 tip & held it on the end of
the brick until a large area of it glowed red. At no time while the
torch was held on the brick or while it was cooling was there any
smoke or aroma. After the flame was removed there was no
decomposition of the brick & very little discoloration.

Dave


#7

The “silversmith” bricks from the brickyard sound like standard
firebrick Very useful, indeed, but not the same as "magnesia"
blocks. Firebrick is low-fired, porous ceramic (primarily alumina
and silica). No magnesium. The block I was asking about is even
lighter, sort of fibrous and solf to the touch, though a similar
pale tan color. Does anyone use such a soldering block successfully
(without it smoking and burning)?

I also worry about anything fibrous–will it effect my lungs the way
asbestos would? It all depends on the size and shape of the fibers,
not so much what they’re made of.

Noel


#8

Hello Beth, Dave, et al, I use kiln bricks. They are soft enough to
push dressmaker pins into and can be sawed up with a hacksaw. Broken
ones were free at a brickyard, although that’s been a couple decades
ago. Maybe someone who uses a kiln can report on what is
currently available. Judy in Kansas


#9

Your "magneia block"supplier is selling sometying other than what
the term applies to.

"Magnesia " would indicate magnesium oxide a very high temperature
refractory melting at 2800 C. They are used as a high temperature
facing refractory in steel making. They stand up to heat but have a
high thermal conductivity and are not "insulating’. True magnesia
blocks would not have a binder and would not melt easily. You are
obviously being sold some fibre or powder based material with an
organic binder. Maybe fiberfrax or kaowool board. These would be
good to about 1200 C. They would also be eaten into by borax type
fluxes. They will usually have some organic binder that will burn
off on first heating.

In the case of ‘silversmiths bricks’. They’re 2 1/2" x 4 1/2" x 9" &
weigh 1# 14 oz.

They’re soft enough that pins can be pushed in with your fingers.
These would usualy be called “insulating firebrick” and would be
easiest to find at a ceramics supply house. Using the term
"silversmiths brick would probably bring a glazed look from most
suppliers. They are very lightweight - you don’t want the
hardsurface refractory firebrick.

jesse


#10
    To be real honest, I don't know the exact chemical makeup of
the bricks. I get them at a local brickyard. There, they're called
'silversmiths bricks'. They're 2 1/2" x 4 1/2" x 9" & weigh 1# 14
oz. They're soft enough that pins can be pushed in with your
fingers. While they're smooth, they have many holes that may be the
result of small air bubbles trapped when the bricks were cast. 

Judging by the above description, it sounds like a fire brick; which
can be cleaned by sanding, or rubbing on concrete, etc.

margaret


#11
   To be real honest, I don't know the exact chemical makeup of
the bricks. I get them at a local brickyard. There, they're called
'silversmiths bricks'. They're 2 1/2" x 4 1/2" x 9" & weigh 1# 14
oz. They're soft enough that pins can be pushed in with your
fingers. While they're smooth, they have many holes that may be the
result of small air bubbles trapped when the bricks were cast. 

This is the type of block I started soldering on years ago when I
was a teenager (scary to think that was over thirty years ago). What
I like about them is that they can be carved to hold pieces at
different height as well as hold balls and tubes in place. For years
I searched high and low for them and tried magnesia blocks and was
disappointed with them. Last year I found them at a jeweler’s supply
shop in Denver that I did business with 30 years ago and they still
had them. They call them Oven Bricks and I think sell them for $5.00
each. They lady who waited on me was taken aback a bit when I was so
excited to find them. I told her that I used to do business with
them 30 years ago. She told me her mom must have waited on me
becasue she was too young to work in the store at that time… :wink:

The store name is:

Maroon Bell Industries
3400 Tejon Denver, CO 80211-3435
(303) 433-2283

I don’t know if they do shipping but it would be worth a call.

Rick Copeland
Silversmith and Lapidary Artisan
Colorado Springs, Colorado
http://home.covad.net/~rcopeland/


#12

Hi Beth , I have never used these , but , from your description , I
wonder if pumice blocks would do the same job ? I have seen loose ,
soft blocks - like you use to remove dead skin - up to quite hard ,
solid blocks . The soft ones sound ideal - they probably wont last
long , but should be fairley easy to get , especialy if there is a
volcanic area near you . Just a possible idea .
Philip Wells in sunny Nelson , NZ


#13

What is the advantage of using a firebrick over a high density
charcoal block, if any? Is it price? Are firebricks cheaper? I paid
$22.00 (CN) for a high density charcoal block whereas I would
imagine fireblocks are plentiful and probably very inexpensive. Am I
wrong in this assumption?


#14

I have been using fire bricks for several years. The only thing I
don’t like about them is that little solder bits tend to get lost in
the little holes if they fall off the piece (or if you drop them –
I’m the clumsy type!).

Margaret


#15

I’ve been a potter for 30 years. The white/beige firebrick that is
used to line ceramics kilns can be sawed into many nice manageable
pieces for soldering. Since these bricks can be fired to over 2,700
degrees F, they can certainly take on most soldering jobs. They
take pins and are my favorite for soldering. Go to any bookstore
that carries pottery or ceramics magazines and you’ll find lots of
ads for what potters call “soft firebricks.” You might call around
to masonry or fireplace dealers and have some luck there. I keep a
spray bottle filled with water near my soldering station. When I’m
through soldering, I mist the brick or charcoal so that there is no
danger of smoldering or fire. Hope this helps.


#16

Hi to all, I tried a magnesia block too and didn’t like it. I went
back to my soft bricks from an old kiln or furnace? I’ve had them
for years and like Judy from Kansas I use a saw to cut off the top
of the brick when it gets really gunky (technical term). Then I use
the little pieces to prop up and hold odd and awkward pieces when I
solder. I agree that the solder drops into the holes so what I do
is use fireplace bricks under my soft bricks to place my solder
pieces on until ready for use. They also serve to protect my work
bench. With the exception of making small silver balls I use the
soft bricks for everything. OK well I do have an annealing pan.
I’ve tried almost everything on the market and keep going back to my
old bricks. Mary in really, really hot Yakima, WA (suppose to hit 106 tomorrow!)


#17

All, I purchased one of those bricks many years ago from one of our
jewelry supply catalog companies. Wish I could remember which one -
but have a look through some of yours and you may be surprised. I
do remember Indian Jewelers Supply sells lava rock for direct
casting silver in the “old” way too. Perhaps it was they who had the
firebrick. Good luck, and keep streeeeeetching.

Pat


#18

Judy,

    What is the advantage of using a firebrick over a high density
charcoal block, if any? Is it price? Are firebricks cheaper? I
paid $22.00 (CN) for a high density charcoal block whereas I would
imagine fireblocks are plentiful and probably very inexpensive. Am
I wrong in this assumption? 

I think you hit the nail on the head as far as I know. However,
while I would prefer the reducing properties of the charcoal block, I
always grab for the firebrick if I need to carve into one of them. I
just don’t have the strength to damage “my precious”.

Ryan


#19

Hello Judy, Kiln/fire bricks are usually low cost and last a very
long time. I abuse my soldering surface since I push pins into it.
Charcoal doesn’t take the abuse and wears away with use. The
surface of a brick does get glopped up with flux overspray, whence
the advice to dress the surface by scrubbing it on some concrete to
grind off the gunk. Thin slabs of brick make good props and can be
used to build a little “oven” to hold the heat when soldering large
silver things. I still use charcoal for some things and for making
silver and gold balls. (Before we realized the dangers, a coil of
asbestos held in a metal ring was a common soldering surface that
took abuse and was durable.) I also use a nifty soldering pad made
by Steve Satow, which I bought at the last Orchid auction. It is
very smooth and level and fits the GRS mounting. Bottom line, we all
probably use several soldering surfaces to meet different needs.

Judy in Kansas


#20

Fire brick is more inexpensive but does not offer a reducing
atmosphere that charcoal does. I solder on a honeycomb ceramic
block.

Marilyn Smith