Sealing Oily Cast Iron for Painting

- J
- Joe
  
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posted
20 years ago

Thu, Jul 31, 2003 2:26 AM

I am doing a rebuild on my lathe and I am having some trouble with oily spots of the casting. I have tried heating and cleaning repeatedly, but it wicks oil and the paint won't adhere. Can anyone suggest a way to deal with this? I seem to recall a sealer of some sort that would serve this purpose well, but can't find it from google.

Also, as a side note, I had my lead screw reground and had new half nuts and a new worm gear made by REMPCO for less than $700. I was very pleased with all of my dealings with them and the quality of their work. I am also replacing my compound screw and half-nuts with a precision ball screw. I got it with oversize balls to reduce the backlash to ~.001 and as I will be using a DRO, the .003 per foot accumulated error in the screw was not a big deal to me. Just passing this along as food for thought for others.

- L
- Leo Lichtman
  
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posted
20 years ago

Thu, Jul 31, 2003 3:02 AM

Joe wrote: (clip) Can anyone suggest a way to deal with this? ^^^^^^^^^^ I am pretty sure that shellac will solve your problem. There is also a produce called "Bulls Eye", which is a white pigmented shellac based sealer that ought to work.

- M
- Mark Fields
  
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posted
20 years ago

Fri, Aug 1, 2003 2:12 AM

You might try pressure washing the parts to remove the excess oil. Some of our customers do this after they machine the castings. They probably use an emulsifier in the water. When we have a local oil spot on a casting, we use spray cans of degreasers. They are products manufactured for NDT work, to remove red dye penetrants and/or UT coupling greases, etc.

I don't know how big the casting is, but if you could find a local service that would vapor degrease the castings all the oil should be removed. That's another process that would be a little more costly but more thorough.

You don't mention the type of paint you are using, but all the machine tool manufacturers we have made castings for (Milacron, LeBlond (and Makino), Hitachi, Okuma, Toyoda, Monarch, Mazak, Gleason, etc. ) want Polane type coatings. These are the best for machine tools. They are also often used on other industrial machinery for which we make castings.

Mark Fields