Been reading a few of the posts regarding sand blasting models.
I will respectively disagree with the numbers I've seen for abrasively blasting
models.
You should never use more than 35-40 psi to sandblast a model especially a
brass model. Many models have sheet brass that is tack soldered to represent
doors and access panels. Air will blow under the panels and stretch a bubble in
the brass panel that won't come out. It's there forever. And it will happen.
100 grit aluminum oxide is just too coarse for model work unless you are
weathering wood structures or items. You will find 220 a better grit size. 220
will not feed through the Badger blaster. The Badger gun works OK but is not
designed for any real long term blasting without using a blasting cabinet and
having a handful of extra tips.
Tape off all but what you want to blast off a plastic model. Turn the air
pressure as low as it will go - 10-15 psi is fine with the right equipment - to
start with. If it doesn't work well enough, slowly increase the pressure. Keep
in mind most lettering that is pad printed will be harder than the surrounding
paint areas. You can blast right through the sprayed finish and the lettering
will remain. So go slow.
The Scalecoat paint removed is good for most plastic models along with other
home remedies. But I never recommend brake fluid. It is terribly invasive and
will find crevices you never see until after the fluid has leaked out on the
fresh paint.
Biodegradable paint removers that are safe for brass usually work fine.
Airplane paint stripper is a little more expensive but you never use much so
the speed is helpful.
I've used gallons of Acetone to soak bad paint jobs before blasting. But it
must be done in a closed container left outside. If you have doubts about
solvent safety, don't do it. You can blow up the house and your neighbor's
house.
The true cleaner of properly etched brass or plastic model is a 6-10 drops of
Dawn in a quart of water is about the right ratio. Rinse twice in clear water.
Blow dry with a clean, dry air supply and set it aside to air dry in a dust
free container. Wear your latex gloves to handle it while painting. Water will
migrate to every solder joint and just wait until you hit the it with paint to
blow out on the model surface.
And the last item, no glass beads. Bead blasting with glass beads does nothing
but peen the surface and will lead to paint chipping. High air pressure
compounds the problem. You can only truly etch the surface with bead blasting
when the beads have been broken down with sharp edges. Every time you handle
the model, after the paint truly hardens, induces micro fissures in the paint
surface. It will crack. Maybe not this year. But it will eventually crack.
Abrasive blasting with a hard edge abrasive is the only safe method that will
truly etch the surface the way it should be.
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