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Alloy identification

I have several small ingots of something I thought was lead,however
it is marked “CERROLOW-136 ALLOY” I am concerned about melting it
without knowing the constituents.


Bismuth 49%
Lead 18%
Tin 12%
Indium 21%

I hope that helps,

You have a special low melting (136F) bismuth based alloy see:



It’s a bismuth alloy with a 136 F melting point. Composition is Bi
49.00% Pb 18.00% Sn 12.00% In 21%. Bismuth alloys tend to expand upon
solidification, usually continuing to expand for hours after
solidification. Some typical uses are exact duplication of a cavity,
or for holding a delicate or irregular object. This particular alloy
has minimal expansion but is rather expensive, do a google search
but make sure you are sitting down.

I have successfully used the less expensive 158 alloy while putting
large and deep stamps in models meant to be rubber moulded. Similar
contamination precautions as with handling lead, but the melting can
be done with hot water and the alloy is a lot harder.

Demand Designs
Analog/Digital Modelling & Goldsmithing

Hi Tom what you have is a special low melting “fusible” alloy that
melts at 136 degrees F it is made up from Bismuth 49%, Lead 18%, Tin
12%, Indium 21% (BTW the indium makes it quite expensive).

Do not try to melt this with a torch you will ruin it and will likely
vaporize the lower melting metals which are not good to breathe. It
will melt nicely in a double boiler or on a hot plate but make sure
to use a stainless steel pot to melt it in as it will alloy with
aluminum and ruin both the pot and the metal. It is a great material
to fill the inside of tubing for bending it can also be used to make
short run press forming dies. Lots of uses.

Here is what a couple of websites have to say about it

  CERROLOW 136 alloy is used for proof casting, testing and
  inspection, anchoring parts for machining (jet blades), block
  lenses in optical manufacturing, fusible element in fire
  sprinkler heads and other safety devices, fusible cores on
  compound cores, sealing adjustment screws. Is a low temperature
  solder and in hobby applications. Cerro low 136 is a eutectic
  alloy with a melting temperature of 136 F. Initial expansion
  then shrinks to .0000" per inch in one hour. 

  Prior to 1930, Bismuth alloys existed chiefly as laboratory 
  curiosities. They were known to have very low-melting
  temperatures  and low physical strength and a few had been used
  as low temperature  melting solders for safety devices like
  sprinkler links, plugs in compressed gas tanks and in fire
  alarm devices. 

  INDUSTRY EQUIVALENTS: AIM 58,  AsarcoLo 136, CerroLOW 136,
  Indalloy 136, Ostalloy 136 

Jim Binnion

James Binnion Metal Arts
Phone (360) 756-6550
Toll Free (877) 408 7287
=46ax (360) 756-2160

Member of the Better Business Bureau


I remember playing around with alloys of this type when I was at
school (many, many years ago when chemistry lessons involved real
chemicals and everyone got their hands dirty!). We used to cast the
alloy into the shape of teaspoons and put them in the teachers
commonroom - when they used them to stir their tea, the spoons simply
melted to a puddle in the bottom of the cup…

Best Wishes,

Ian W. Wright
Sheffield UK