Can anyone recommend a cheap citric based degreaser? I need to clean
old petrol varnish off a long unused motorbike tank as it is currently
flaking off and blocking the fuel cock.

AJH

On 14/10/2017 19:57, wrote:
Can anyone recommend a cheap citric based degreaser? I need to clean
old petrol varnish off a long unused motorbike tank as it is currently
flaking off and blocking the fuel cock.

AJH


Not sure I would be confident that modern limonene degreasers (such as
Citricent) will actually attack the lacquer/varnish that can be formed
by oxidised hydrocarbons. That said, I associate such lacquer/varnish
polymers more with lubricating oils than fuel.

Assuming your problem is correctly diagnosed, I think I would start with
mechanical attack, for example some sort of sand blasting. You might
follow this up with something like angular granite chippings, either
shaken manually or perhaps putting the tank on a mechanical shaker at
all necessary orientations.

Also, your fuel cock should have a wire mesh filter protecting the
intake. You must have a *lot* of material coming off if this is causing
problems. Which makes me think that a sufficiently aggressive mechanical
attack would soon separate almost all of it.

Is it *really* varnish, or mostly rust? If rust, then any strong acid
should sort it (hydrochloric, sulphuric, nitric). You might consider
phosphoric.

Is it *really* varnish, or mostly rust? If rust, then any strong acid
should sort it (hydrochloric, sulphuric, nitric). You might consider
phosphoric.


Does phosphoric acid remove rust, or does it convert rust to iron phosphate?

On 15/10/2017 22:03, wrote:


Is it *really* varnish, or mostly rust? If rust, then any strong acid
should sort it (hydrochloric, sulphuric, nitric). You might consider
phosphoric.


Does phosphoric acid remove rust, or does it convert rust to iron phosphate?

Yes.