Blast media finishes

[WinDancer]

I bought glass beads for my new sandblaster.

I can't get the finish as dark as I would like.

Is there a general rule about blasting steel? Like the finer, more abrasive media gives the steel a darker color, while the larger gives a lighter color?

Or ????

Dave

[Geno]

Dave,
I don't blast my blades, but the grit wouldn't change the color(I don't think)
If you use a rougher grit and a dye, that would give you any amount of darkening desired.
I use a black laquer paint thinned(per batch) for consistancy, and brush it on, let it dry, then lightly sand, or wipe clean with laquer thinner. It leaves a dark background in the pits and darkens the blade as much as I want.(depending on how thick the black is)
This coating should be baked on too.
Do this before temper, and soak in the oven like a regular temper.
The paint becomes very hard and gives a protective coating on the blade too.
There are other solutions you might use too, this was just one idea.Black laquer is fairly common in damascus making to highlight contrast of steels and showing texture.

[Colin KC]

Dave,
If you use glass beads, you'll get a satin type finish that is smooth(ish) to the touch & does appear quite light.

Aluminium oxide, or garnet, will give a rougher finish (easy to strike a match with a small movement) & what appears to be a darker finish (a couple of shades) this is due to the sharp profile of the surface as opposed to (with glass) a very wavy surface.

Using these more abrasive mediums will, however, work against any stain (read: rust) resistance your steel will have.


Hope this has been of some help

[wrathlord]

I found it is the amount of alumina in the mix,and the size of bead,I notice the finer the micron the finer the finish,the gun and rate of blast is also important,smaller cabinets used to finish jewelery and stuff have much finer venturi's so the blast is more precise.The bigger industrial cabinets have guns usually and the finish with that is sandblast in a contained unit.The bead is much bigger and rougher.That is what I think your looking for.The beadblast is more of a flat grey coating,as opposed to the rough sandblast.

[Raymond Richard]

Dave, Haven't done any glass bead blasting for sometime but when I did I felt like I was spinning my wheels when starting off with glass bead. Found my results were so much better if I started with 150 grit garnet and then went with the glass bead. The glass beads pean and work much better is the surface is ruffed up with the 150 grit garnet first........