Naval Jelly

l008com

Senior Chief Petty Officer
Joined
Jun 14, 2007
Messages
730
So I pulled off a lot of vynil this year, and I have lots of rust stains from staples that were pressed against the fiberglass for ~25 years. I've tried a few different rust stain removers, regular scrubbing, and a mr clean magic eraser. The magic eraser did a little, nothing else did anything. I really want to get rid of this rust so I can try to fill in the bolt holes. I've used naval jelly in the past on steel and it worked really well. Can I use that on my boat? I wanted to check first just in case it eats fiberglass or something.

Here's a good picture of the rust. There's rust where the staples were in contact with the fiberglass, and also around the holes where there were bolts holding it all together:
 

ajgraz

Lieutenant Commander
Joined
Mar 1, 2010
Messages
1,858
Re: Naval Jelly

Naval jelly (phosphoric acid) is just going to turn the rust stains black.

You need to find a rust stain remover that contains hydrofluoric acid (HF). Check label or MSDS.
 

l008com

Senior Chief Petty Officer
Joined
Jun 14, 2007
Messages
730
Re: Naval Jelly

So I just did a little research with my chemicals. Yes my naval jelly is phosphoric acid. Although it has worked great in the past, why do you say it's going to turn the stains black?

The worst of the chemical I tried was West Marine "pure oceans" stain remover. It was like spraying water on my fiberglass. I was so pissed that they sold me that crap. I took a picture of the label so I could tell you what it contained, but my phone's camera sucks and you can't read the label.
Same with the Works shower cleaner. That stuff melted away my years-old water stains instantly, but did nothing for my rust stains. The other chemicals I tried had no labels, they came from a bulk canister into a small spray bottle.

*this* reply is pretty useless. I planned on listing all the acids I tried but thanks to my low quality camera. . . meh.
 

i386

Captain
Joined
Aug 24, 2004
Messages
3,548
Re: Naval Jelly

Naval Jelly (and Ospho) contain phosphoric acid as stated eariler. It converts rust (iron oxide) to ferric phosphate which is black.

The black ferric phosphate can then be scrubbed off metal using a wire brush. Not sure how well this works on fiberglass.

Ever thought to try some CLR? Just an idea.
 

saildan

Petty Officer 1st Class
Joined
Mar 7, 2009
Messages
264
Re: Naval Jelly

There's rust where the staples were in contact with the fiberglass, and also around the holes where there were bolts holding it all together:

Match the stain to the chemical or visa-versa.

CLR might work,

CLR FAQ
Can I clean my fiberglass boat, tub, or shower stall?
Yes, CLR is safe on fiberglass. Begin with a mixture of CLR and water and progress to full strength if needed.

Oxalic Acid (rhubarb juice) works - called wood bleach at the hardware store and found in Bar Keeper's Friend cleanser at the grocery store.

Also found in StarBrite Boat rust cleaner, Rust-Off, Whink Rust Stain Remover.

Most of these will tell you it's contact time not strength that does the work. A mild solution soaked on a paper towel and plastered over the stain for 20 min can work better than a splash, swipe, or spray & wipe of the same solution in a higher concentraton.


;)
 

Yacht Dr.

Vice Admiral
Joined
Feb 26, 2005
Messages
5,581
Re: Naval Jelly

Hello m8s..

For most rust stains and scum lines try some toilet bowl cleaner ( snow bowl or equivilant ). Works wonders :)

Just let it sit there for those hard stains .. may have to repeat. Rinse well after wiping off.

Its an ol boaters trick ;)

YD.
 

sasto

Captain
Joined
Jun 1, 2010
Messages
3,918
Re: Naval Jelly

I have always used diluted phosphoric acid on rust stains and brown waterline marks. A gallon is cheap. The Yacht DR's use of toilet bowl cleaner works great too. I really like it on bronze props and running gear too.
 
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