Sure. Just start doing it.
It took me 200-300 carbs to get decent.
By carb 850 I really had it consistently good.
Strip old coatings.
I do this with 90C lye/tsp mixture. Be aware, too long will destroy the casting.
Use an mild acid to activate and neutralize the bases. Be aware, too long will destroy the castings.
Dip in a standard yellow chromate. Time and temp are depending on your chromate recipe.
You can use the old publicly available Chronak process. Or buy a ready made one.
Tho to be honest, if you are in EU likely hex chromates are probably not attainable.
You can also make your own yellow for castings. This works better than Chronak process.
200mg sodium dichromate, 200ml sulfuric
Be aware this will heat up to 160C nearly instantly and is incredibly dangerous, kinda eats unexposed flesh. .
Rinse chromate crystals with nitric while vacuum filtering.
This makes chromic acid. Be aware it is a powerful oxidizer, so best to do with with sealed containers and a fume hood.
Use that chromic acid and find a ratio with nitric and sulfuric that works well for you.
Your brown/grey/yellow/iridescent looks depend upon your chromic to sulphate ratio, so experiment.
Also be aware that there is an expensive and involved process to dispose of hex chromates… basically you need to turn them to the trivalent state etc.
Took me 3-4 years a s probably $12,000 to get my setup working well.
The best chromate book is by Biestek, I bought a copy in Frankfurt actually.
Good luck!
