Subject: glazing over sandblasted surface?

From: Paige Dean <[email-masked]>
Date: 13 Jun 1996 13:10:17 GMT

I have searched via deja-news for info but finally deciced to post, I am 
a regular on rec.woodworking but this is my 2nd time here so I hope I'm 
not posting this question for the 314th time this week...

I restore old (40's-50's) woodworking equipment- planers, etc. I am not 
satisfied with my finish of blasted parts. The castings are sprayed at 
time of manufacture with some kind of building primer and when I blast 
the parts I am down to the raw casting. I use Sherwin Wms Acrylic Enamel 
and Jet-Seal primer. Sometimes I use glazing putty but that is a real 
pain. The autobody supply house said I could use an epoxy primer but I 
would have a lot of sanding. The guy who blasts my stuff is a propane 
outfit so he uses coarse sand and a lot of pressure. I am thinking of 
finding someone who uses corn cobs, pecan shells, etc. I have used a 
tumbler bead blaster at an automotive machine shop but still have the 
rough as-cast surface. Also, some of these parts are cast aluminum. 

Any advice will be greatly appreciated!!

PD

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From: "John R. Johnson" <[email-masked]>
Date: Thu, 13 Jun 1996 11:49:46 -0500

Spend a few hundred bucks for a bench-top bead blaster cabinet and bead
blast the parts.  You might try using automotive primer/surfacer.  It is
a much heavier product that is designed to fill small surface imperfections.
It can then be smoothed with sandpaper and sprayed to get a first class
finish.  

John

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From: Mike Rehmus <[email-masked]>
Date: 15 Jun 1996 18:25:28 GMT

Find youself a guy who blasts car bodies using plastic
or chemical media.  He can control the blast to take
off the top coat and leave the primer.  Frequently
this is used on plastic-bodied cars so it does work.

You should probably not attempt to take everything down
to bare metal unless there is a lot of rust involved.
If so, consider glass beads or walnut shells.

If you do a lot of this, you might want to get into the
blasting businss yourself.  At least you can then pick
the media, pressure and angle at which the abrasive
stream hits the work.

I've sandblasted several autombiles in my driveway with
good success.  I use low pressure, #30 sand, and shallow
angles.  Of course portions of my driveway border look
very much like the Sahara!

Have you considered one of the spot blasters that are used
for automotive work?  They don't leave much mess and are
very controllable.

If you do blast, make certain you observe the safety and
health precautions.

Best regards,

Mike Rehmus

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From: Mike Rehmus <[email-masked]>
Date: 15 Jun 1996 18:27:16 GMT

By the way,

You cut most of the excess body putty off with one of 
the cheese-grater tools before it completely hardens.
Never let the putty completely harden before you rough
shape it.

Best,

Mike Rehmus