Is it safe to mix hydrochloric acid (36%), phosphoric acid (45%) and oxalic acid (5%) in a water solution?
The mixture will be used to remove hard clay deposits from the hull of a boat. Can you recommend a gel in which the mixture could be suspended to make application possible by brush?

How big is your boat and what's the hull made of? A boat wash is where most people go and use a high power wand washer and then soap. About where are you and where do you plan to wash your hull?

Bet an RV wash may even be useful.

The boat is a bilge keel 8 metre yacht that's been craned out of the water. I'ts been high-pressure/temperature steam/water jet-washed. I'm in the Thames estuary which is notorious for its sticky clay and each year or so boat/yacht owners face the same problem of preparing their hulls for a new anti-foul coat. It takes a lot of elbow grease and scraping. In the US there is a brand of hull cleaner with hydrochloric, oxalic and phosphoric acids that works exceptionally well in similar circumstances but is unavailable here in the UK. I will become a local hero in my marina if I crack this perennial problem - a lot of my pals will be saved numerous aches and pains from the odious marathon of scraping and sanding come the spring.

Have you tried to get in touch with the manufacturer in the U.S. and see if you could become a distributor. It might work out to be a good side job if not banned from the U.K.

Chuck