Paint and Polyurethane

I just want to see if others share this experience....
they say you shouldn't do it but I have had really good results with
spraying a light coat of polyurethane over my painted surfaces.
I'm talking about aluminum parts which I have....
primed and dried well (a week or more) with canned rustoleum primer
painted with a good quality can spray paint (rustoleum -- krylon) and let dry again, a week or more
sprayed a couple of light coats of the fast drying minwax spray can satin polyurethane
It makes a huge difference in the ability to keep light scratches from even appearing.
Anyone else? -- yet they say poly over paint is a big no no.
?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Rustoleum is a particuarly soft paint in my experience - why not just use Imron or a poly of your choice to start out with? a good 2 party poly or epoxy paint will stick to aluminum just fine
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Not familiar with Imron -- I'll try it.
Easier, no doubt.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Is the Imron a can spray or do I need to use a gun and compressor?
I'm trying to stay away from the HVLP gun for the moment -- I have used professional finishes (like Polane) before -- just can't take the mess and health hazards.
So, for little prototypes, been trying to fine a simpler method.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Imron takes a good filter mask, preferred air supplied helmet. Is a nasty stuff to the body.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Calif Bill wrote:

Using a filter mask when painting Imron will kill you.
Pretty simple there.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Mon, 9 Mar 2009 07:24:42 -0700 (PDT), mkr5000

=======Be sure to read and follow the MSDS to the letter.
The fumes are *HIGHLY* toxic. Several people have died using a regular paint respirator.
Also be reminded that if you do this at home the fumes can easily drift from the shop into the house. As the fumes are heavy they tend to concentrate at floor level where the ankle biters and rug rats live. Also some pet species are even more susceptible than people, such as birds and some reptiles.
Unka' George [George McDuffee] ------------------------------------------- He that will not apply new remedies, must expect new evils: for Time is the greatest innovator: and if Time, of course, alter things to the worse, and wisdom and counsel shall not alter them to the better, what shall be the end?
Francis Bacon (1561-1626), English philosopher, essayist, statesman. Essays, "Of Innovations" (1597-1625).
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
follow this link for truck/automotive http://pc.dupont.com/Phantom/content/imron-comm.html but this variant is what I had in mind http://pc.dupont.com/dpc/en/US/html/visitor/b/dic/home.html
If you go to my web page and look under hobbies/tools, the drill press pictured is painted with the industrial imron. It's much less nasty than the older stuff
I've had good luck brushing it on when I didn't want to mix up enough to spray - and a little hardner added to the mix goes a long way.
data sheets are here http://pc.dupont.com/dpc/en/US/html/visitor/b/dic/s/product/dic.html

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Bill Noble wrote:

$41 a /quart/! You treat your machines a lot better than I do. As long as mine work & aren't rusty, it's good enough.
YMMV, Bob
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Have to agree with the other poster, Rustoleum isn't what I'd use on objects that are getting a lot of mechanical wear, very soft stuff. I use an epoxy or polyurethane paint for such things. The problem with using poly varnish is that it usually doesn't bond very well with paint under it. Sometimes it doesn't even bond very well with itself, I've had gun stocks I was finishing have the last coat peel right off, insufficient mechanical bonding. I don't use it now for such items. For items that need the maximum protection, there's always automotive two-part urethanes, with and without a clear-coat. Automotive stuff is about the toughest finish you can get as a civilian.
For polished aluminum, there are clear lacquers which will give you some scratch and ding resistance and still stick.
Stan
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

As far as compatibility goes, I think Rustoleum "Crystal Clear" Enamel works pretty well as a topcoat over the other rustoleum spray paints.
It seems to "get hard" faster than the typical Rustoleum stuff (which is really slow without baking) but it's not a shortcut, you really have to make sure the bottom coats are thoroughly hardened IMHO.
There are both water-based and oil-based polyurethanes, maybe the warnings you got about incompatibility are the result of mixing an oil- based spray paint with a water-based polyurethane. I know that on wood, putting a coat of latex over oil, or oil over latex, is a real no-no unless the bottom is really thoroughly super-duper hardened first. Otherwise you're just sealing in a unhardened layer that won't harden because of the sealing.
Tim.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.