How do i know when Naval Gelly has done its job?

[75jf40sanpedro]

Hi everyone, I am using Naval Gelly to remove the rust from my floor pan and gas tank. how do i know when it is ready to apply the primer? is it when it turns black? or is it suppose to look shinny and no rust at all? I left it over night and washed with tsp but i still see the rust I applied another coat of the gelly.

Thanks.

 

[george_tlc]

Well, naval jelly is basically phosphoric acid in a gell base. It converts rust (iron oxide) to a stable product (iron/ferric phosphate) that is black in colour.

Up to you if you want to scrub/scrape the iron phosphate away to bare metal before you prime, i.e. the naval jelly will NOT produce a nice shiny metal surface after it has converted the rust.

Obviously to apply the jelly you need to have a CLEAN surface - degrease & clean before applying the jelly so that it can 'get' to the rust.

It can take several application cycles to get most/all the rust out. If the rust is thick/flaky, then you need to scrape off the iron phosphate to expose more rust for the next application of the jelly. Take your time, easier to get rid of the rust 1st time versus having to redo the job later...

cheers,
george.

 

[75jf40sanpedro]

Thanks for the information. I will repeat the process until the rust is out.

How risky or bad is it to use sulphuric acid to ones health? Is the acid always going to be active in the metal eating it away? I used tsp to wash it off.

 

[77mustard40]

Thanks for the information. I will repeat the process until the rust is out.

How risky or bad is it to use sulphuric acid to ones health? Is the acid always going to be active in the metal eating it away? I used tsp to wash it off.

Stay with phosphoric acid, you should be able to pic it up at some of the home improvement warehouses. I started with navel jelly and it works well on parts that can be washed and cleaned after the application(s) but phosphoric acid is great for tougher applications.

 

[75jf40sanpedro]

Stay with phosphoric acid, you should be able to pic it up at some of the home improvement warehouses. I started with navel jelly and it works well on parts that can be washed and cleaned after the application(s) but phosphoric acid is great for tougher applications.

Thanks for the info....I will do that I have used phosphoric Acid before and the guys over at the harware store recomended i use Naval gelly instead.

 

[Kernal]

Could I jump in with a question: is naval jelly/phosporic acid better than say grinding the rust away or bead blasting??