Types of brazing flux
Changing the type of brazing flux you use can yield different results in the brazed parts. There are 3 types of flux we will talk about: White flux, black flux, and purified flux. Black flux tends to be more forgiving and can yield much better results than White flux. Some people still prefer white flux because it allows them to see the work more easily.
In some ways you can compare using white flux over using black flux for brazing to using a .410 single shotgun to using a 12 gauge automatic shotgun for bird hunting. It requires a much higher skill level.
There are different types of black flux. We sell 3 different types of black flux: standard black flux, purified black flux, and mega flux.
Standard black flux does not meet the new purity standards. It is made with about 20% to 30% inert materials. It is great for exterior use, but if you use standard black flux between parts being joined the 20-30% of inert materials will deposit and weaken the joint. It is still possible to create excellent joints with this material. And millions of braze joints are made with standard black flux every day.
Purified black flux meets all standards for purity. Purified black flux is 99% active ingredients and makes for a much stronger braze joint.
Mega Black flux also meets all standards for purity. Mega Black flux is purified flux redesigned. It is sort of like the difference between conventional television and high definition television. They both do the same job, but they do it differently. Mega black flux has about 78% more cleaning power and much easier clean up, and makes the parts shinier. In addition, brazers really prefer it.
Removing hard to remove brazing flux
Brazing flux is an oxygen interceptor. Flux gets really hard to remove when it is heated to the point where it is “all used up”. One trick to remove brazing flux is to apply more brazing flux and then reheat the part to the point where the brazing flux becomes active (not the brazing flow temperature). Usually a couple of hundred degrees is hot enough. The newly added brazing flux will mix with the “used up” brazing flux and the ending result should be much easier to remove once it has cooled.
To aid you in your brazing, we have found some great tools or products we like that seem to really aid in brazing process.
Brazing Aids
1. We like ceramic rods as pokey sticks. They are more fragile than
steel but they don’t get hot.
2. Braze Stop – A chemical you paint on that stops the flow of braze
alloy. We use this when we want to apply braze alloy to anything with
threads. We can braze the top of a bolt and leave the threads totally
clean with this.
3. Heat Stop Paste – A thick sludge made of a mineral that absorbs
water like a sponge. Put it next to where you are welding or brazing
and it will keep that area cool because the water will evaporate.
Once all the water has evaporated you have a chemically inert dust.
No problems with fire or reactivity. No health issue as long as you
don’t breathe it.
Tags: black flux, Brazing, brazing flux, white flux
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