Embedded oil migrating into paint?

[Jelly]

I've just begun refreshing my hand-operated drill press.

Having stripped the paint with paint stripper, removed the rust with Jenolite, wire brush and emery paper, washed down with water, tidied up some more with emery, cleaned with acetone and rags (twice) and cleaned with dry paper... (A pretty thorough pre-painting clean I figured)

On applying etch primer I've had a skim of oil start migrating into the paint leaving dirty marks and crazing.

I'm waiting to see what happens when it dries, to call whether the paint has adhered well and can be saved with a good sanding before undercoating, but assuming I will have to strip and repeat the whole process.



Anyway, the nub of the question is how could I have predicted this before painting (given the parts appeared to be spotlessly clean), and if I do strip it and repeat, what the best way to prevent this happening again.

All advice gratefully received.

 

[clogs]

u dont say if it's part assembled or wether it creeps out of the solid cast iron castings or from a shaft / bearing hole...
so guessing it's in bits, unfortunatley cast can be quite spong like.....even from the old days......
in times past they used red lead or similar as a base coat.....the odd oil stain didnt matter so much then....
BUT when new it never got oil on it untill it was assembled.....
if it we're something really special, say cast parts from a 20's Rolls Royce, they would have to be baked to cook off the oil.....

if the location of the stain really bugs you use a different paint product.....and before somebody says something like stain sealer
eventually it will break down.....plus the probs of differing paint proucts....thru the casting

as an add on
most cast iron casting, say gearboxes etc we're always painted inside before assy because oil can creep thru the metal...

 

[hawkeyefxr]

Wiping dow with cellulose thinners may help. We used "Red Oxide" on our work that had been drilled and tapped so oil everywhere. Just a wipe down and a coat of red oxide, was thick ol stuff.

 

[Jelly]

u dont say if it's part assembled or wether it creeps out of the solid cast iron castings or from a shaft / bearing hole...
so guessing it's in bits, unfortunatley cast can be quite spong like.....even from the old days......
in times past they used red lead or similar as a base coat.....the odd oil stain didnt matter so much then....
BUT when new it never got oil on it untill it was assembled.....
if it we're something really special, say cast parts from a 20's Rolls Royce, they would have to be baked to cook off the oil.....

It's stripped, and the oil is coming from the casting itself unfortunately.

Previously working on train castings I've often used a rosebud to burn the paint off, which bakes out and burns off oil, but in such small castings I would want to put that much heat in even if I had got the oxy-fuel torch set up.

Mainly I just hadn't expected this machine to have had nearly the oil exposure to make it a problem.

if the location of the stain really bugs you use a different paint product.....and before somebody says something like stain sealer
eventually it will break down.....plus the probs of differing paint proucts....thru the casting

It's not so much that the stain bothers me as the impact on coating adherence, as I work through the workshop I'm trying to get everything done with high build epoxy to make it wear and corrosion resistant for the foreseeable future. I know I'm hard on my machines, so ensuring they're easy to take care of and they can stay well maintained is important to avoid just trashing them.

With the nature of epoxy coatings any weakness in adhesion can result in catastrophic failure of the coating with large flakes spalling off, at which point bad things can happen with buried corrosion.

 

[wallace]

I've had good results with brake and clutch cleaner for prepping metal prior to primer