Found Dreaming

If using flux and degassing in which order do you do it, do you flux first then degas or is it the other way around.

Mike

if your using two different chemicals I would flux first as this will flush the oxides to the surface, then use the degassing chemicals which will get rid of the hydrogen that's been absorbed into the melt. you want to do this last as any disturbance of the melt can cause it to reabsorb hydrogen.

Some Commercial Chemicals are designed to do both, and some do the degassing in so vigorous a manner that you have to be very careful when using them in small crucibles cause they can cause splashing or eruptions of the molten metal if too much is used.

But for any of them to work they must be plunged to the bottom of the crucible. I use a short piece of half inch stainless steel tubing welded onto a 1/4" rod cross ways and place paper in the ends to hold the chemicals in, the paper burns, the chemicals melt, and the gas does its thing.

Becareful as some of the chemicals are qutie hygroscopic like the pool shock in that they will absorb moisture from the air, causing even more gas problems.

Harry sells a flux that works quite well from what I have seen with the amount that I have used, it will differently bring the included oxides to the surface which can cause some serious problems in a casting causing it to have weak spots or not be pressure tight if beign put under pressure as in a valve housing or such.

David