Which blasting media for saws?

[jerseyhighlander]

Getting close to paint on the Pioneer 650 and realizing I'm going to need a sandblaster. Found an inexpensive portable gravity fed version that should do well & wondering what type/grit media is best for the saws, both magnesium & aluminum?

One thing I'm noticing with the old Pioneers is that practically none of them held paint very well. The aluminum under the paint being so smooth, I'm hoping the right blasting will help add some tooth to let the primer grip well.

[sweepleader]

Many of the manufacturers did not use primer under their paint. If the paint is not air tight, which seems to the case most often, the aluminum or mag will oxidize under the paint. The oxide is not tightly adhered to the metal so it wedges the paint off no matter what the metal surface finish was like originally. That is the reason the paint comes off in big flakes or washes off easily when the saw is cleaned.

Smooth or rough, I feel there should be quality primer under any paint on a saw.

[jerseyhighlander]

Was absolutely planning on using a self etching primer for the first coats, then to a sandable primer. Acres site says this saw is a Die Cast Magnesium but it looks like Aluminum. Really not certain but haven't put it to the test yet.

Regardless of adhesion, this saw has a lot of detail in the casting that really makes the sandblaster a necessity, just to get the old stuff off and down to clean metal. I was thinking a medium to fine grit crushed glass media but I've never used it before on Al. or Mag.

[Deleted]

While in the subject of primer and paint, has anybody heard of Bulldog. It’s available at Oreillys and is an adhesive promoter. When I restored the little John Deere pedal tractor of mine I was told buy a guy I work with that paints cars on the side to use it first. I used it then a primer then two coats of paint. It’s cast aluminum and I painted it last spring. It’s been left out in the rain a time or two and driven into the outside brick wall of my house a few times and I have t had any issues of paint coming off....yet. I’m sure the older that boy gets that tractor will run into more. Anyway back to the subject at hand I am soon going to have a C-72 blasted and then I was going to repaint I was thinking of using it on that too

www.oreillyauto.com/detail/bulldog-4072/chemicals---fluids-16461/paint---body-repair-16614/paint---adhesion-promoters-19225/w-m-barr-and-co-bulldog-adhesion-promoter/tpo123b/4402339

[sweepleader]

If you cut a sliver out with a knife you can tell, mag is harder. Compare to something you know is aluminum.

File or sandpaper an area and something you know is aluminum, the mag will be darker.

[onlyhomelites]

I'm using aluminum oxide with great results. It etches the magnesium just enough that a good self etching primer sticks like glue.

[tjthechainsawmech]

I've been using glass bead with awesome results as well. Takes very low pressure and leaves a rough surface for primer.