All the hull cleaner liquids are primarily Muratic acid. You can buy a gallon at Lowes or Home depot for less than $10. Get a plastic paint roller tray and bristle brush on a pole to apply it, let sit for 3 minutes and then rinse with water liberally.
You can buy the bottles with a picture of a boat on them, but be prepared to pay $10+ for a quart
Zud. It is oxalic acid based and will remove the Cooper River racing stripe and other stains that have built up on hull and inside on the deck. Rust stains will be removed also. The brown discoloration is a lot like the soap deposits in your shower. They are actually insol salts.
On Off is muriatic acid (hydrochloric acid) like Redeye said. Good idea on getting it in induestrial form at Lowes, Redeye.
Startbrite Hull Cleaner (the Walmart stuff) is oxalic acid. You can also get it as wood bleach. It’s a lot cheaper that way, too. Didn’t know about Zud. Thanks for posting that.
Both (HCL/On-Off and Oxalic/Starbrite) are strong, caustic acids; gotta be really careful with them. DON’T get either of them on any METAL–espcially the On-Off/muriatic acid. I know first hand that muriatic acid will react violently with metal and literally fizz madly and dissolve the metal. Put a small puddle of muriatic or On-Off on a piece of tin foil and let it sit 20 second and see what happens. It will look innocent for about 15 seconds, and then it will erupt violently. It can literally burn your skin, too, and don’t breath the vapors. Oxalic is pretty wicked stuff, too.
Acetone is fingernail polish remover–the stuff your wife dips her fingers in once a week. It’s cheap and not as hazardous to health as the acids, but it’s still pretty strong stuff. It cleans most things well, but probably not as well as the powerful acids (I’ve used it in the past because I feel safer with it and it was readily available to me, and it worked well for me). Don’t get it on any plastics or in your eyes. And don’t sniff it. 
There may be some things one product cleans better than the other and vice versa.
BTW, it’s always a good idea to check the MSDS (Material Safety Data Sheet) before using chemicals. All of these chems are harsh. That’s why they clean stains so well.
Gotcha Covered,
Lee Strickland
Strickland Marine Insurance, Inc.
843-795-1000 / 800-446-1862
quote:
Originally posted by redeyeAll the hull cleaner liquids are primarily Muratic acid.
I was thinking that it is Oxalic Acid. And I have looked for it in bulk to no avail.
I do have a gallon or two of Muriatic Acid and I will give it a test try. (see research results below)
Anytime I ever worked with muriatic acid, it bubbles when it hits the concrete, (I think masons use it to clean brick work) And it will definitley remove some grout from tile work (tried it one time with bad results). I never seen oxalic acid bubble or foam on concrete
I have also seen muriatic acid used to clean aluminum as in running boards and other aluminum products.
This discussion led me to research this for about 30 minutes. It seems that Muriatic Acid is a cheaper solution but much more caustic and can cause harm to your skin (burn and scar), your plastic parts on boat, definitley ruin chrome, and painted finishes, I read that it can remove galvanize from trailer. Make certain to implement safety protection gloves and eye protection.
If you choose to use muriatic acid, make certain to dilute plenty and rinse well after application…
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Muriatic is hydrochloric acid. If you look at the MSDS, you’ll see that the concentration of the On-Off is 20-25 % and the concentration of the Lowes bulk muriatic is 20 something percent too. Either will destroy and burn your skin. It’s dangerous crap no matter what. And something they used to pound in chemistry class was, “if you dilute acid, make sure add acid to water, and not water to acid”. That is, put water in a bucket, and add the acid to it. Otherwise, it could overheat and splatter. On-Off may actually be a little more hazardous than the Lowes muriatic because On-Off also has Oxalic and Phosphoric acids in it.
BTW, Smily, if you want to buy oxalic in bulk, look up “oxalic wood bleach”. It’s much cheaper per wieght than the oxalic-based hull cleaner (Starbrite). It comes in crystaline form in buckets. Add to water to dilute. It’s very nasty stuff too, though. Be even more carful if you buy it that way, because it’s concentrated.
Gotcha Covered,
Lee Strickland
Strickland Marine Insurance, Inc.
843-795-1000 / 800-446-1862
Smily,
Here are the MSDS’s (Material Safety Data Sheets) for the products suggested above:
Starbrite Hull Cleaner (5-10% oxalic acid): http://www.starbrite.com/msdssheets/81732-msds-7-25-06.pdf
Oxalic Acid (100%): http://www.jtbaker.com/msds/englishhtml/o6044.htm
On-Off (25% HCL): http://www.jamestowndistributors.com/userportal/pdfs/MSDS/on_off/on_off_hull_cleaner.pdf
Muriatic/HCL (20%): http://www.sciencestuff.com/msds/C1819.html
Muriatic/HCL (33-40%): http://www.jtbaker.com/msds/englishhtml/H3880.htm
Acetone: http://www.jtbaker.com/msds/englishhtml/A0446.htm
Gotcha Covered,
Lee Strickland
Strickland Marine Insurance, Inc.
843-795-1000 / 800-446-1862
Lee, thanks for the good advice/research on cleaning products. I’ve got most of a gallon of Muratic acid left over from laying an epoxy floor in the garage and looks like I just found a new use for it. I used to use bleach and water in a bug sprayer to get all the stains off the boat. I’d spray it down with the solution, let it sit, then hose it off. Sounds like I’ve got something new to try.
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A lot of people use bleach, but it’s a strong oxidizer, so I don’t use it.
Gotcha Covered,
Lee Strickland
Strickland Marine Insurance, Inc.
843-795-1000 / 800-446-1862
I have a 25 Kilo drum of Oxalic Acid that I’ll part out. $5 lb. I used to work at a chem company, and requested a SMALL sample from a rep. Well, I had to buy the sample. You dillute 2 ounces of the powder to a quart of water and spray the hull. As soon as the stain dissapears, hose it off. I’ll never use what I have, as I haven’t put a dent in the drum in three years. If you have a rust stain, add enough water to make a paste, and rub it in the stain. I have been told that it will etch the finish if let sit too long, so I always dillute it less than what was recommended. I saw a product at the N.O. boatshow that was for this purpose, and it was $15 pt. with just distilled water and Oxalic acid which is why I bought the drum. So, if anyone wants a lb, PM me.
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