What's new
What's new

I have no idea(paint question)

EndlessWaltz

Cast Iron
Joined
Jun 18, 2016
Location
Midwest
Hey guys,

I restore older drill presses here and there. Recently having a weird situation which I do not understand, but I am sure someone here will know for sure. I sand blasted some parts with aluminum oxide. Sat a few days. Maybe,..maybe...some light rustish color. Anyways I have paint matched before using just a simple acrylic latex paint from Menards. For a drill press it is fine for what it is. Throw a layer of paint on. Next day...wtf...rust/beige discoloring all over. This is a gray paint mind you. Today I put another layer on and I think it is happening again! The only thing I can think of it has something to do with the sandblasting. Reason is because another part was already stripped by someone else and the paint I put on their is just fine.

So explain this to me like I am 5yrs old.
 
Let me get this straight, you paint metal working machinery with with water base, latex paint? You avoid dozens of redundant threads here repeatedly discussing paint attributes by some of the the most experienced machine builders available. Your attempt fails and you're appealing for help? Five years old about covers it.
 
Paint shop engineer here.
After sandblasting, hit the clean steel with Ospho, or another metal prep that phosphatizes the steel. Follow the directions. Use a red oxide primer, Rustoleum works fine. Now, you can use an oil base enamel in your favorite color to finish the piece.
There are some Direct to metal acrylic paints out there that work reasonably well. Latex would be my last choice.
The water in the latex rusted the metal and bled through the paint. You won’t get great adhesion, and I would expect the metal will be rusting under the paint..
 
Have seen panels stripped of paint and the entire underlying surface is all brown with rust.
Don't you like those red primer cans that say you can paint over rust.

If I had no other choice then it would be phosphoric acid coating and then the cheap paint.
 
1) Most guys here debate which paint is better blah blah for their "perfect" restoration * case in point is no one agreeing what red is used on a Ford 8n .
2) I know what red etching primers are etc. Remember I had done this once before, with SAME EXACT paint and I can attach pics of the drill press in all it glory still being use by my father(fathers day gift) for fixing his farm equipment all these year later and the paint looks just fine. If it ain't broke don't fix it..(if this was a serious use item like a mill or lathe you bet I would be using better paints)
3) I clearly explained this was happening on only the parts I sand blasted. Remember..there was another bare metal part this was not happening to in same environment right next to other parts.

Thank to those who who calmly and precisely explained what may be going on. It makes sense that I opened the pores by sandblasting , rust may have been starting, and then I just made it worse.
 
1) Most guys here debate which paint is better blah blah for their "perfect" restoration * case in point is no one agreeing what red is used on a Ford 8n .
2) I know what red etching primers are etc. Remember I had done this once before, with SAME EXACT paint and I can attach pics of the drill press in all it glory still being use by my father(fathers day gift) for fixing his farm equipment all these year later and the paint looks just fine. If it ain't broke don't fix it..(if this was a serious use item like a mill or lathe you bet I would be using better paints)
3) I clearly explained this was happening on only the parts I sand blasted. Remember..there was another bare metal part this was not happening to in same environment right next to other parts.

Thank to those who who calmly and precisely explained what may be going on. It makes sense that I opened the pores by sandblasting , rust may have been starting, and then I just made it worse.
Sandblasting gets the metal completely clean, and the surface now is a bit rough, so moisture will cause very rapid flash rusting. Phosphatizing makes the raw metal resistant to rust (not rustproof). Then a good primer will do a good job of sealing and protecting the metal. Once primed, you can use most any topcoat you want. Latex will work after the priming step. However, it does not always adhere well to an oil base primer.
 
So explain this to me like I am 5yrs old.
This is like telling a 5 year old that there is no Santa Claus...

Any brand of 1 part paint does not full harden. Take a spray can job and try some sand paper on it. Comes off.
Now try some sand paper on a 2 part paint job. In some cases its like using sand paper on concrete. That issue
along with some others made me hang up the rattle can and convert to automotive paint brands.

Worth the expense and not that big of a deal if you just roll it or brush it. If you spray it then a fresh air breathing
mask protects you the best.
 








 
Back
Top