Heat sink compound

Leu Custom

Leu Custom

Joined
Jun 2, 2007
Messages
1,354
Does anyone know where to get heat sink compound that can withstand 600-700 degrees? Thanks in advance!
 
Lots of sources. Places like K&G, TKS, Jantz, etc. usually carry it.

One caveat - Heat sink compound does not really protect metal from heat conduction. It protects the SURFACE, from a flame used around it. Applying heat sink compound to a blade surface when soldering on a guard will help from accidentally getting the flame on the blade edge and ruining the temper. It won't keep the blade from getting too hot if a continued flame is applied to the guard at high temps, as in brazing.
Stacy
 
I saw something being used as a heat sink awhile back that I had not thought of. A potato with the blade stuck through it.
 
yeh got the brownells stuff. According the Stacy (Bladsmth) it's pretty useless for what i'm trying to do.

A potato eh? Temper my knives and have lunch afterwards! :D
 
Sorry Stacy but I have to disagree about heat sink pastes just protecting the surface. We use it all the time in the HVAC business and the purpose isnt to protect the copper but rather the nylon/plastic seals in componets that are being brazed on. Some of the ones we tried evaporated so fast they were useless in our application but thermotrap(from Johnstone supply) works well and is inexpensive. Needs to be applied about 1/8" thick,more if you want.
 
When I solder on my guards I have a couple aluminum plates that I bolt on the blade where it starts. That way any heat that gets in that area is radiated off thru the plates. My solder melts at under 500 but, I want to make sure my edge stays under 400 and they are usually only a short distance away from each other. Jim
 
I piddled around with such products for a short time until I discovered the simplistic pleasure of just wetting some ceremic wool and putting in where I want with spring clamps.
 
When I first worked as a goldsmith in a jewelry repair trade shop we didn't have any fancy heat pastes to protect sensitive stones when we were soldering the items they were set in, the practice in the shop was to wrap the stone in paper towel, wet thoroughly and make sure it stayed wet the idea being that as long as liquid water is in contact with the stone the stone surface where the water is never gets over 212 fahrenheit. I now use gels to protect stones, but the principle is the same, as long as there is water, it will absorb heat (the gel just makes better contact with the stone) I have tried using the gels on blades when soldering guards, but the amount of heat I have to throw at things to get the brass guards up to draw solder means i am fighting the gel, and either it runs out of water, or draws off too much heat for a good joint. I have been contemplating the idea of the aluminum plate heat sink in combination with a tray of wet coarse sand, as I am trying to come up with a foolproof technique I can teach my students.

-Page
 
Sunshadow has pointed out the problem with many heat sink compounds.
A heat sink, by definition, absorbs (sinks) the heat from an object that it is in physical contact with. The ability to "sink" heat is relative to its thermal conductivity, and its total mass. The bigger the heat sink, the more heat it can absorb. With paste compounds the ingredients are designed to transfer the heat without drying up too fast. High temp oils and silicone compounds are used to get past the 212F limit of water. The mass of these is quite limited, with about 1/4" thickness being about all you can add in most applications. For brazing guards on knifes, the heat applied (BTUs) is usually far in excess of the rating of the compounds.
For quick soldering copper tubing on HVAC units (400F-600F temps, short duration, and low BTU input) it works fine. Pohan was going to use it for tempering in an oven ( 500-600F, hours of time, and HUGH BTU input),where it would fail totally.
As others have pointed out, if you are using the low temp solder to seal the joint of a guard, a wet rag is all the sink you need. The whole joint should never exceed 450F, lower with some solders.
Stacy
 
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