Temperature Crayons: anybody used them?

tried tempilstick brand once, by the time the steel got up to temp I couldn't see the crayon mark due to everything being the same dull red and the forgescale.
get a pyrometer, thermocouple etc, and pay attention to the color the steel is when it is certain temperatures, you'll be happier

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I have used them, but much prefer the paint.
The crayons are actually more like chalk...

I use the paint doing the differential temper on the spring section of my ECS.
It's much friendlier to work with.
 
The crayons aren't meant to be drawn on and then wait for them to melt. They are meant to allow constant checking of the temperature, by trying to draw on the material. At the rated temperature they will melt and leave a mark.

I've never used the liquid type. I use the crayon type all the time assisting my customers who are heating and installing bearings.
 
I've used tempilsticks quite a bit for preheating (for welding and interference fits - I'm a welder by trade). They work fairly well but are not really meant for precise temp measurements. The sticks melt at or above (this is important to remember) their rated temp. meaning that once the stick will melt, you do not know the exact temperature (only that it is higher than the stick's rating). They are also not well suited for through heating or cases where you want to hold temp. for a while, as they indicate the surface temp of whatever you're testing (not necessarily the same as the temp. beneath the surface - especially when dealing with a varying or thick cross-section). For tempering, you want to hold a constant temp. for a specific length of time (soak) to get consistency through the cross-section of your blade - tempilsticks will not be any better than judging by heat-color. If you want to temper without blowing your paycheck on a kiln, use a pyrometer or pyrometric cones (pottery or ceramics supply stores will have them) inside a forge or toaster oven. It's not nearly as good as investing in a heat-treat oven, but it will work way better than the sticks.

Have a good one,
Nathan
 
Thanks for all the info guys; it was very useful.

I am trying to flame heat-treat some shuriken, which are just square-stock spikes.

The results aren't very critical, so it sounds like the tempsticks (or paint; either one) could work to give me a rough idea of the temperature.

Since I don't know temp by the steel's color, I thought the tempsticks might help me learn that association.
 
I humbly suggest the paint.
It's more expensive, but also much more friendly in your instance.
The sticks only melt at or above temp, so it's difficult to get to just "THE" temperature with them.
You just can't tell when you are getting close....

The paint liquifies at temp and stays melted above temp.
It's easier to eyball that you are approaching temperature, and add and remove heat to stay in the ballpark with the paint.
You'll see what I mean when you use it.
You can just tell when you are getting close with the paint...
 
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