Oxalic Acid boat hull cleaner
Where to buy oxalic acid powder
How to mix your own and apply it
Where to get pre-mixed hull cleaner
Where to buy Oxalic Acid in the USA
Note: prices jump around, so compare these various vendors ' current prices - prices listed here are current as of April 2016
1 lb bag of oxalic acid $9.00 + free shipping ($9/lb)
2 lb bag of oxalic acid $9 + free shipping ($4.50/lb)
5 lb bag of oxalic acid BEST DEAL! $15 and FREE shipping ($3.15/lb)
The plastic jug you see in the photo is 6 pounds of oxalic acid…probably a lifetime supply for me.
The recipe and instructions are further down on this page.
You want pre-mixed hull cleaner?
Star brite Instant Hull Cleaner gets rave reviews. FIVE STARS! It should because it's 5--10% oxalic acid! You can read the exact ingredients of Star Brite Hull Cleaner here.
Last time I looked it was $20 for 32 ounces (a quart) of Star Brite. And free shipping iwith Amazon Prime. Let me do the math…let's say it 8% oxalic acid because they say it's between 5 and 10 percent. 8% of 32 ounces is 2.56 ounces of oxalic acid. I'll be generous and say the oxalic acid is $5 a pound (although you can get it for around $3/pound).
$5/16 oz = $ .32 (32 cents an ounce)
$ .32 x 2.56 oz = $ .82 (82 cents)
Star Brite is good stuff and it will work for you, but you are paying over $16 for them to mix it up and put it in a bottle for you. You can make a quart for under a dollar.
Save $100 making your own!
I looked up a store-bought hull cleaner's MSDS (material safety data sheet which lists ingredients) and lo and behold...it is 1 to 5 percent 2-Butoxyethanol (a degreaser, like a soap) and 5 to 10 percent oxalic acid! Let's say it is 8% oxalic acid…that's about 2.5 ounces per quart. At $16 a quart on Amazon, you're paying about $102.40 a pound for the oxalic acid.
So pre-mixed is about $16 a quart. If you mix up your own it's about fifty cents to make a quart!!
How to apply and use
First off, wear gloves and goggles when using oxalic acid.
Applying it is simple. At first we wiped it on with a rag.
Later we used a gallon pump sprayer, sprayed it on and let it sit for a few minutes. Then we went back and hosed it off with lots of water.
Don't leave it on metal for long. It can remove rust, but also zinc from brass.
For really thick algae growth, I scraped the hull with a plastic scraper (I even used a plastic ruler sometimes).
You may want to apply a good wax or other coating after cleaning.