I'm looking at getting some Tamco Moncoat for axles and small parts but their Q&A says "Do not use any form of rust converters..." but if you neutralize like in video don't see why it wouldn't work.
https://tamcopaint.com/products/monocoat-1-k-direct-to-rust?variant=31399920566352#qamp-a_i1
For Tamco products, the reason they advise against using converters is the likelihood of the product not being neutralized or removed completely before applying product on top of it.
Think of something like a door that has a hemmed edge, phosphoric acid can easily creep into that hemmed area, you prep the panel, it’s still in the hemmed area, spray epoxy, then it starts creeping and bleeding out causing adhesion issues.
And certain products, like Monocoat, 5311, some of their epoxies are DTM/DTR, so they already have the ability to seal the rust on their own.
I’ve used monocoat, I like it, but if you are going for more visible parts and want them to look really good, I’d recommend their HB truck chassis black paint or their underhood satin black products.
I have used their chassis black for the frame and parts of my 79, I have a gallon on the satin to use for the inner fenders and underhood stuff.
79 12 Bolt in chassis black:
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Their 5311 primer is really good stuff too. I primed my trailer fenders with it almost 2 years ago and the trailer sits outside in the elements and still look like the day I sprayed them.
If you reach out to Barry at SPI or the Barney’s at Tamco, they are both receptive to questions about their products.