Subject: Re: Machinery prime and paint?

From: [email-masked] (Chris Kantarjiev)
Date: 20 May 1996 18:47:01 GMT

Anyone know how to do this right (well, as best I can in 
	my home garage without spray equipment)...

Without spray equipment, eh? Then you can't do it "right" ... but no
matter, you can do a really nice job.

The state of the art in painting metal comes from the auto industry.
Painting is easy - surface prep is what's hard, and the better
the surface prep, the better the final finish.

First you want to remove all the grease and dirt. I prefer a solution
of trisodium phosphate - buy the powder at a hardware store and
mix it up strong. (Be sure to get the real thing, not a lookalike
that's labelled "TPS".) If there are parts of the tool from
which you'd like to remove old paint, this is a good way to do it -
get a galvanized bucket big enough to hold the part and soak it,
preferably over a stove to heat the solution and speed the reaction.

Washing down with some sort of phosphoric acid solution is a good
idea; it will etch the steel to take the primer, it will neutralize
the microscopic rust that's in the steel's "pores", and it will leave
a thin iron phosphate layer that will resist surface rust while you
continue. Naval Jelly is good for removing rust, but needs to be
rinsed - you want something that will flash off. DuPont makes a product
called metalprep that is expensive but very good; find it at your
local auto paint store.

Just before I paint, I wipe down everything with lacquer thinner or
something like PrepSol to get any surface dust or finger grease off.

Get a primer that goes with your paint. Most automotive finishes aren't
meant to be brushed, so your auto paint store will be helpful here. I
*love* PPG DP40 - it's a very tough finish in its own right, etches
the surface a bit so it really hangs on. Follow the directions carefully,
especially regarding mixing and timing (DP40 wants to be painted over
in no more than 36 hours, for example, or you have to scuff it.) Most
auto paint stores will mix up paint or primer and load it into a rattle
can for you, for a price.

Good luck.

---

From: Anthony EPucillo <[email-masked]>
Date: 21 May 1996 00:00:49 GMT

I've been waiting for somebody to suggest this in response to a painting 
inquiry, but they haven't, so here goes.

If you want to primarily prevent corrosion, Zinc Chromate is one way to 
go (don't breathe it ... _really_ ... but it's available at 
marine/aviation outlets in spray cans).  Some of the Epoxy-chromate 
paints are probably harder, but you don't want to get into two-part 
paints for your project.  Zn Chromate is sort of soft, but _very_ 
effective against corrosion.  I use good old Rust-O-Leum spray right over 
it, with results at least as good as the factory gets on equipment.
ROL is a better paint than most people think, and given half a chance to 
harden up is pretty durable, too.  Discount store spray paint _is not 
Rust-O-Leum_.

     For a piece of shop equipment getting hard use, I'd personally use 
a paint something we use in auto restoration a lot (when you want to do 
something _once_ and never do it again, however long the blasted car 
lasts).  It's a moisture-cured urethane (not _poly_urethane; totally 
different) and is sold under several names, one of which is "POR-15" (by 
a company of the same name (800) 457 6715) another is "Miracle Paint" 
(Bill Hirsch Ent. (800) 828-2061) --  and it's advertised in J.C. Whitney 
Auto Parts (item 12FG1079R: Black; 12FG1080X: Silver; (312) 431-6102).

    This comes in three "colors" (if clear, black and silver are colors) 
for about $25 to 28 a _quart_).  Don't use clear for anything exposed to 
sunlight, since it will cloud a bit.

    This paint is kind of an open secret of auto restorers, and is 
impervious to everything.  You can paint an anvil, let it dry, whack it 
with a hammer -- repeatedly -- and just dent the anvil and the paint with 
it.  You can immerse it in salt water for months, with no result 
whatsoever.  It hardens even more with age and exposure to moisture, and 
you will never have to paint again., One trick is to use it on sheet 
metal that is almost rusted through, and the paint is so strong it 
restores the strength of the metal itself.  Candidly, I wouldn't bother 
using a primer, though I'd use a pre-treatment "etch" to be sure you get 
a good tooth to the metal (chemically-cleaned pitted metal is the best 
surface you can have for this)  A primer just IMHO wastes the awesome 
adhesion of this stuff.  It's sprayable like any other paint and is a 
one-part paint, though you may want to thin it a bit to spray (don't 
recall if it uses a special thinner, they'll tell you when you order).

    I've used this on a car frame which then sat for three years 
outside, in Florida.  The frame was almost rusted through where it 
_wasn't_ painted, but looked brand-new where it was.  I sprayed the 
silver on the 5/8" CDX plywood my utility (read: trash can) carts are 
made of, which have been out in the sun and rain for _eight years_ 
without even a splinter in the wood (all sides and edges heavily sprayed 
and permanently preserved).  They haven't absorbed a drop of moisture, 
even though the edges are exposed and unprotected except for the paint.

    I don't think this stuff is terribly toxic, as paints go, but _do not 
get it on you_, or if you do clean it _soon_ or you will wear it until 
the skin wears off.  No kidding: I sat on a newly-painted surface and 
didn't notice 'til it was too late.  I wore a stripe for a good month.

    Interestingly, though I've always sprayed it, I've seen this paint 
brushed on, and it's so slick and heavy-bodied, you can't see 
brushstrokes and it looks sprayed.  It also covers all pitting.  JUST 
DON'T USE IT ON ANYTHING YOU MIGHT EVER WANT TO STRIP AND REPAINT.  
Short of UV, I'm not sure anything will touch it.  A quart goes farther 
than you might think, by the way.

    Even if you don't want a silver or black drill press, if you have 
this stuff around you'll use it for something (put any left over in a 
smaller container and put a layer of plaastic wrap between the container 
and top.  You will never get it open again otherwise;  I've had to cut 
the top off of more than one partly-used can.)

    Again, I have no affiliation with any seller, and they wouldn't want 
my endorsement anyway.

---

From: Allan Anderson <[email-masked]>
Date: Sun, 19 May 1996 22:12:43 -0700

I just bought a grimey, slightly rusty old Walker-Turner
2 head drill press (that works well enough). I'm cleaning
it up and want to paint it to prevent future rust.

I'd really appreciate some pointers about how to get a 
solid paint job. I've got some machinery gray Spray-on brand
Acrylic Enamel (for machinery) and I was thinking of getting some 
primer for automotive use. Someone suggested a cleaning with 
phosphoric acid to neutralize any active rust (news to me...)

I'd appreciate your comments....

Thanks!

-------------------------------------------------
Allan Anderson
Response Computing, Inc.
3701 East Minnehaha Parkway
Minneapolis, MN 55417