Duda Energy 1 Quart / 950ml 85% Food Grade Phosphoric Acid Rust Remover Clean Etch Metal

If you are still buying the pre-mixed 10% or 20% pH Down from the grow shop, you are literally paying for expensive water. I switched to Duda Energy’s 85% Food Grade Phosphoric Acid for my 100-gallon reservoirs, and the cost savings are insane. One gallon of this concentrate will last me as long as 5–8 cases of the 'brand name' stuff. It’s food-grade, so I don't have to worry about impurities messing with my root zones. It’s extremely clean and stable. Because it’s 85%, a little goes a long way—I only need a fraction of what I used to use to hit my target 5.8 pH. If you’re a high-volume cultivator, this is a no-brainer for your bottom line.

85% is a very strong concentration for phosphoric acid. I used it, after brushing away loose scale, on rusty cast-iron, wrough, iron, and steel plant stands that we have all over the place. I let the acid treatment sit for a few hours to a day to dry, follow that with a light rinse and dry again, then touch up (spray) paint. It takes longer in terms of duration, but the effort level is lower than sanding and brushing down to bare metal, priming, and then painting. I suggest diluting this acid at least 50-50 to start. You can adjust up or down from there the higher, the concentration you use, the longer it will take to dry, and it tends to take on a greasy sort of feel if the concentration is really high. High quality.

I use it for removing rust & it works fine. I like the thickness too.

I dilute this to use as a flush for my boat diesel engines and air conditioners on my boat. It saves you a lot of money over buying the pre mixed commercial flushes available. Using phosphoric acid versus things like muriatic acid dissolves the particles., mollusks and helps keep your cooling passages clean. My boat is in a saltwater environment. So I have to flush those air conditioners every two to three months during the summer time or I start getting high pressure alerts on the air conditioners. For another tip, add a small copper fitting snd bromine tablets into the strainers to your engines and air conditioners to help reduce mollusk and algae growth.

You put copper in a 20% solution and it turns bright, shiny, and smoousth. Better than it was, new. I've used it on iron rust too as preparation for repainting an old rusty outdoor chair. The rust was too thick to make the steel shiny, but it served the purpose. I'm sure it would work with many other metals. Prior to the invention of carbonation for soda, around 1920's they'd put a tiny drop of it in a soft drink. Its nice enough, though you can see why carbonation has replaced it. It is a real acid so treat it like one! You should dilute this stuff before using. OTOH, if you get some on your skin, you have time to run to the sink and wash it off before you get burned. Safer than, say, nitric acid. And strong acid is fun to try for all sorts of uses in the garage! Do not use w/o adult supervision.

I used as rust prevention and so far no rust. I have used this product in the past and it will not stop rust from forming but it caused it to form much slower. An annual application and your metal, iron/steel, should last as long as you do.

Works great for all sorts of things food grade acid is good for. I bought it to clean my water softener and it's resin bed. Works amazing. Made my 7 year old resin soften hard well water like it's new again. Good price too

I wanted food grade phosphoric acid for homebrewing non-alcoholic beers, which require a pH adjustment to get below the food safe range of 4.6. I've lost some batches to infection in the past because I've not acidified my wort. Approximately 3mL of this 85% phosphoric acid solution drops the pH of a 5 gallon batch of wort from around 5 into the low 4's. Due to the small amount used, no perceptible flavor is imparted. It came packaged well and tested at the proper pH (0.5). Obviously, this is a product for people who understand safe handling procedures of strong acids.