Plastic media blasting is now used extensively to remove paint and coatings
from metal surfaces such as airplanes etc.
The difference between the plastic blasting and sand or glass blasting is just
that. The media is small plastic pellets, projected at the painted surface to
be stripped, by a high velocity stream of air. The "plastic grit" chips off
the paint or coatings through impact of the collision. The plastic media
offers a level of compliance that minimizes the disruption of the substrate
surface. This is a problem with formed sheet metal surfaces.(fenders etc.)
when sand blasted or other more aggressive processes. During the forming
process, stress is introduced and trapped at the surface of the metal sheets as
tension or compression. The core of the material is at the neutral axis, and
experiences only bending. If the surface is acted upon by some effect that
disrupts these skin stresses, the part will "move", or deform from it's
intended shape. This makes a fender or other body part that no longer fits or
just looks bad. The plastic media will not smooth scratches, but may burnish
the high edges of scratches by bending them over and back into the scratch.
This might better be done with a burnishing tool. Body filler works wonders.
Sanding is always a good idea as a bit of "tooth" can only aid adhesion of the
paint to the surface. Chemical etches can accomplish this also.
Glass bead blasting is somewhere between grit (Black Beauty) and plastic media
blasting. In its true form the glass beads are just that, small hollow glass
beads. The mechanism of their breaking up on impact is how the energy is
transferred to the painted surface and so removed. Glass bead blasting does
not permit reuse of the abrasive media. Most operations routinely ignore this
aspect.
regards
Calvin Grandy
Vermont
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>
>
> Just a little question. What exactly does bead blasting do to the metal
> surface on the car? Does the surface have to be finish sanded before
> priming, etc.? Will the procedure remove surface scratches?
>
> Paul
> 67 1600
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