[Amps] spray painting metal

Roger sub1 at rogerhalstead.com
Fri Jul 31 12:28:07 PDT 2009

Glen Zook wrote:

Above all, do the painting in a well ventilated area and expect paint on 
every thing in that area when you finish.
If you do the painting outside as I often do, make sure your neighbors 
cars are not outside down wind.  You can end up painting cars half a 
city block away and they may not be ready for a new paint job yet.  
Beware the two part cyanalic paints.  They are deadly and require a full 
suit with supplied fresh or tank air. If provided from an acceptable oil 
free compressor the intake must be upwind and external to the paint area .

I see a post from Carl with some good information just popped up as I'm 
typing this.
> Another thing, to prevent "runs", if possible paint on only a horizontal surface.  With practice, it is possible to paint on a vertical surface.  But, painting on a horizontal surface is definitely easier.
I was taught to always to paint an entire cabinet section at a time. The 
reason is the the over spray. which leaves a hazy finish at the joint 
which is normally very visible if done one section at a time.  If you 
get runs it means too much paint. Hence the several light coats instead 
of one heavy. I hang (or suspend) the cabinets so I can do the entire 
cabinet at one time.  HVLP (High Volume Low Pressure) sprayers are much 
better than conventional this way as they have little over spray. This 
makes them much more efficient , but I found  one to take *me* much more 
practice after 50 years of using a conventional. <:-))  Most paints do 
not require as much thinner when used in an HVLP gun, either.
> Also, priming a metal surface definitely makes for a better paint job.  A lot of the "boat anchor" manufacturers did not prime the metal before painting.  In those cases if you just paint over the old finish quite often the paint will start to peel.  Frankly, in most cases, it is best to take the cabinet, panel, etc., down to the bare metal, prime, and then paint.
Hallicrafters was an exception to this.  I've never seen primer and the 
finish appears to have been baked on, but I've never had it peel. OTOH 
it will chip and where it's chipped over painting will show. Quality 
paint over the old Hallicrafters shouldn't peel if the surface is 
properly preped. For chipped surfaces I'd use a good chemical stripper 
but check for disposal requirements. Some are much more environmentally 
friendly than others.If the cabinets are not badly chipped, careful 
sanding, or a good working over with "Scotch Brite Pads" of the fine 
variety and then cleaned and wiped down with mineral spirits should work 
well. After drying paint should stick quite nicely.

When painting aluminum be careful in removing the old paint. I would 
suggest not sandblasting as that stretches the metal and Aluminum can be 
quite fragile in that case. Commercial sandblasting can even stretch the 
Hallicrafters cabinets. One of those is a real hand full and most of us 
unlikely to personally use one.  I spent a good deal of time on one at 
work before all the OSHA regs. A full suit and breathing air was 
mandatory. The little paint sprayer size sand blasters work fairly well 
if you have enough air pressure and volume, but they are slow for large 
jobs. Again do outdoors and wear a good dust mask, not the little ones 
we see for dust and pollen.  A full face mask would be advisable. Also 
sand blasting does not leave the surface ready for painting.  Aluminum 
needs to be etched. The reason is surface of bare Aluminum Oxidizes 
almost immediately. Steel cabinets will show visible rust over night.
You can find etches at auto paint stores, or Aircraft Spruce. Self 
etching primers are also available.  I would suggest staying away from 
Chromate primers which are a corrosion proofing material that is getting 
very hard to find. The EPA considers it to be a problem. It was used as 
a primer on most aircraft until recently.

BTW it's relatively easy to build a good, portable paint booth for about 
$20-$30 using plastic water pipe, fittings, sheet plastic (drop cloths) 
a window fan with a furnace filter to fit and a wee bit a duct tape.


Roger (K8RI)
> Glen, K9STH
> Website:  http://k9sth.com
> --- On Thu, 7/30/09, Charles Harpole <k4vud at hotmail.com> wrote:
> My dad, the furniture man, taught me how to spray paint with a pro gun or just with a spray can. The tricks include
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