Cast Iron Clear Coat Stains

Hi,

I'm in the process of restoring an old craftsman 113 table saw. I currently working on the table top (cleaning the rust, sanding etc.) and after reading quite a bit about clear coat I decided to go with water-based polyurethane coating. After applying a thin coat (which dried almost immediately) I notices yellow stains across the table top. Can somebody explain why this is happening? Is this rust? can it be removed? what other options do I have?
I didn't encounter this issue in any video/review/discussion about the subject.


Thanks in advance
Yuval
Attachment 443898

Most of the time I just use Johnson's Paste Wax. Nothing else. Personally< I would never put any water based finish on cast iron. That is just asking for trouble with rust. If you are bent on using poly, why not an oil based poly?

Regarding Johnson's Paste Wax, I live in Israel and so far I couldn't find that product here (so I will look for a different type of wax..). I'm also a bit concerned about the maintenance required for wax coating and whether it attracts sawdust.
Apparently oil-based polyurethane doesn't stick to the iron that good and is not recommended.

Location challenges ;-) I also have never applied a clear coat of any kind to cast iron. If rust is a real problem where you are there will be a little more work involved than for those of us in lower humidity areas. I have no experience in Israel so I have no idea of the products available. Johnson's Paste Wax is just a specific brand / formulation of paraffin (petroleum derived) and hydrocarbon based waxes in a solvent carrier. Minwax, Knapp and others make paste wax prducts. I would think any similar product in your area would work. A lot of people avoid any sort of car wax as they tend to contain silicon and other additives for polishing and "shine".

Hi, Thanks for the advice! What do you think about beeswax (managed to find it in Israel so I'm asking)? is it an good? I read that it is a bit sticky.

Yes that is rust. The same reason you don't use steel wool between coats of water based finishes.

Johnson's paste wax is wax is used on wood floors. The house I grew up in the oak floors had no finish of any kind., Just waxed about twice a year. I would guess even candle wax dissolved in solvent would be okay. you are looking for a hard floor wax. Many have carnuba wax in the mix.
Bil lD.

I think this outfit ships to Israel?
https://israel.desertcart.com/products/1485798-sc-johnson-paste-wax-16-oz-1-lb

I see a seller on UK Ebay buit they want over $25 for a tin.
A reasonable price here is 10-15$