How do I refinish a cast iron tub?

Try calling in the pros. I have had several tubs professionally reglazed with excellent results.

https://www.doityourself.com/stry/how-to-refinish-a-cast-iron-tub

Hi Anita, this is Peggy. Sorry you are having a hard time refinishing your tub. Have you tried appliance paint? Worth a try and good luck

Its all about the prep work..... http://www.klasskote.com/epoxy_bathtub_paint

prep... http://www.klasskote.com/files/3863370/uploaded/bathtub%20instructions%20-%209-26-19.pdf

Porcelain tubs are etched with an acid first... https://www.amazon.com/XIM-44082-Etching-Cream-1-Quart/dp/B000EW7LLK/ref=as_sl_pc_qf_sp_asin_til?tag=klasskote-20&linkCode=w00&linkId=f105575e91aa095074a1fe3d61e3d59b&creativeASIN=B000EW7LLK

You will have to remove the old paint first.

You could try finding a professional as sometimes tubs can be tough to refinish on your own without professional tools

My uncle was trained in old bathtub, sink and porcelain restoration over 30 years ago I have two OLD tubs that desperately need refinishing. I sent him pictures of the tubs, unfortunately, he lives several hundred miles away. He told me to call a professional refinisher. He said he's worked on too many tubs, especially cast iron, which have been more costly for him to restore due to the time and work required to undo the owners failed diy attempts.