Oxalic Acid Hull Cleaning

[John Marrone]

When we got our 1987 Catalina 22 there was a lot of hull surface oxidation. Used the typical McGuires products to remove the oxidation and applied polish tfor protection of new finish. Once back in the water there were areas where oxidation had not been completely removed.
Thinking about using a diluted Oxalic Acid solution on the Hull to once again clean all the oxidation off the surface and start over with finishing compounds.
Any past experience or other suggestions are greatly appreciated.

 

[sail sfbay]

To remove oxidation generally involves the following How to Restore Chalky Gelcoat on Your Fiberglass Boat or Yacht (jjsboatservices.com):

1. Wash and Remove Surface Dirt and Debris
2. Remove Stains
3. Wet/Dry Sanding - this is the key
4. Polishing Compound
5. Waxing and Sealing with Protectant

 

[Hayden Watson]

Here is a good article. If you cannot find the gel that is recommended here, you might also look for Davis FSR (Fiberglass Stain Remover) I find it at my local ACE Hardware.

 

[Parsons]

The absolute best advice was from our own MaineSail, and there is a long following post where other members rave about how good a job it does - Tips For A Great Buff & Wax Before you start, (1) this is not quick or easy and (2) you will never think that anything less than mirror-finish is acceptable for your boat. Refinishing well will last for years with only minimal waxing annually. BTW: it is not fun to do.

As for cleaning, the first step is to clean with Oxalic or Marykate On and Off - my favorite as it comes as a gel and sticks very well. Remember in using acids that they can permanently scar your lungs if mishandled, so use some brains and get an acid-rated mask, a Tyvek overall, goggles and gloves to save yourself.

 

[shemandr]

I have used oxalic acid to remove tannin stains. I'm not sure why it would work on oxidized gel coat. An oxidizer to remove oxidation? Maybe our resident Chemistry professor can enlighten me?
I think oxidation needs to be abraded off - sand paper, compound, scratch pads etc.
When I refinished my aluminum oxidized mast I sanded off the oxidation. But we do use acid products to clean up stainless, so maybe.

 

[RoyS]

When I worked for a Transit Authority I engaged several chemists to recommend an effective and inexpensive cleaning product for the Imron painted car exteriors. The recommended product was an oxalic acid based solution. The exterior body cleaning was mostly done by drive through automatic washing machines. The areas not reached by the drive through machine were done by hand with the same oxalic base product. Oxalic acid diluted with water was used for years with no harm to the paint evident. Imron paint is similar to Awlgrip paint. We had no gel coat so I can not speak to that. Despite what you pay in a marine store for an oxalic acid cleaning product the chemical itself is inexpensive. We had it delivered by tanker truck. Great cleaner.

 

[Siamese]

Ditto on the Tips For A Great Buff & Wax

That's how you do it right.

 

[Jacktar]

Try Sno Bol toilet cleaner, hydrochloric acid containing gel, (sticks to vertical surfaces so you can scrub it )only about 3 bucks a bottle, works great on marina oil, gas and slime stains.

 

[Capt Robbie]

bar keepers friend porcelain and stainless cleaner works just as good as on off and only about $2.99 at the super market. I don’t recall what the percentage of Oxalic acid it has, however I’ve been using it for years and works just as good as on off and for the price, I don’t think anyone could complain. Just sprinkle on a wet brush and scrub lightly, let set for about 5-10 minutes and hose off. Done. I don’t think it will do anything for oxidation, however that’s the first step if you need to compound hull.