Short term rust preventative

[metalcleaner]

Looking for a short term rust prevent for mild steel which is not oil based and has no silicone. Parts cleaned are reject painted parts which are thermally cleaned and then dipped in muratic acid to rinse the ash and need short term protection(3 to 5 days) before being repainted in a wet and powder coat paint system . Would like it to be sprayed on due to the size of parts and the size of tank needed if dipped.

 

[unclesyd]

I would look at a H3PO4 based wash primer. You can get with a chemical supplier and he can probably put you on several products that would do the job.
I have a fried in the coating business that uses this approach with very good success. He is able to paint or powder coat directly over the phosphate surface.

If you would like to get a product to check this out go to the big box store and look for Wedac or Ospho.

I would look at using a H3PO4 product to clean you prats after they are thermally cleaned and kill two birds with one stone.

We thermally clean thousands of parts by Pyrolysis and don't have to resort to an acid clean. At most if is dust blast with glass beads.

 

[sshep]

My experience is only chemical cleaning of carbon steel process equipment, but after the acid cleaning a "passivating wash" is used to give short term protection (a few days) from rust while the equipment is open to humid air. The most common of these washes in my experience are solutions of: sodium hydroxide, ammonia, and/or sodium nitrite; although my chemical cleaning manual also suggests: sodium carbonate, or sodium phosphate. The wash solution is then rinsed with condensate of pH=8.5

Some of these chemicals are good alkyline solutions that can also be used to nuetralize any residual acid. Usually NaOH or ammonia are satisfactory for protecting acid cleaned equipment during shutdown work. Sodium nitrite is used for longer protection. I don't know if surfaces so treated would then be too passive for your coating process. This is my experience which suggests that the treatment solution required for a few days protection does not have to be very exotic.

best wishes,
sshep