fisheye in paint

[jackleg007]

i finished some mild steel by grinding the dross,scuffing the surface ,but leaving most of the mill scale on,and painting.the paint turned out pretty good.

now i have been trying to remove the mill scale and dross by soaking in vinegar.the vinegar works amazingly well,and the dross removal and grinding is very minimal and in a matter of minutes i am down to bare metal.the problem im having is now the paint fisheyes badly when i paint it...i have had to wash off the paint with thinner on a bunch of projects,and repaint.

any ideas why this is happening?after i wash with thinner,it is a lot better,but seems like that should be unnecessary to do this.obviously ,i may have to wash everything with thinner before the first coat,although i dont know where the problem is coming from.has any one had the same problem?i have been looking at a product called wash and wipe,its used by bodyshops to prewipe cars before painting.has anyone tried it.

also,i painted a peice straight out of the vinegar.let it dry before painting,no grinding.paint came out nice.any idea whats happening after i grind off the mill scale residue?

[fyrpower]

talked to a buddy who paints cars he said it is some kind of contaminate left on steel, he said to try wiping down with lacquer thinner before painting.

[jackleg007]

thanks,will give it a try

[Arcs.sparks.art]

I have had good luck with using soap, dawn dish liquid or purple degreaser from Walmart. I use a car wash type brush to scrub them down hose off with fresh tap water, air dry then paint or prime paint. I have a friend who says he only uses Steel which is pickled and primed, little cleanup, he has most his work powder coated. I have toyed with idea of using a dish washer... Best of luck...

[1fine79]

It's some sort of surface contamination for sure. oil, wax or silicones of some kind are the major culprits. couple things that come to mind...1) check the discs you grind with, some contain silicone as an additive and grinding just embeds that into the surface. 2) skin oils from handling can also be an issue espeacialy if you're using automotive grade paint (very nice finish but very unforgiving). rubber or disposable gloves might be an option.
Also, keep in mind that any kind of airborn contaminates anywhere in your shop can create problems. ie...using lubricants like WD40 or anything with silicones in it can travel airborn for quite a distance. even grinding on oily or dirty material can create a dirty cloud in your shop. I only mention all this because I've had similar issues in a plant where we did our own powdercoating close to where we did our fabricating. we finally had to isolate the two areas from each other and that helped our situation. anyway good luck, hope this helps.

[abmetal]

If you're mixing your paint, you can buy fish eye eliminator in a small bottle from the local automotive paint store and just put a drop or two in the cup. I've used it for years and a bottle of it will last for years also.

Allen