On 24/08/19 09:40, Archibald Tarquin Blenkinsopp Esq wrote:
On Fri, 23 Aug 2019 18:38:47 +0100, Jeff Layman
wrote:

On 23/08/19 14:39, David wrote:

Worth considering using some strong plastic sheeting to rest the BBQ bits
on whilst you are treating them. Acid tends to rot most things it comes in
contact with, especially clothing.

It's not the rotting which would concern me - it's the splashing of the
ferric phosphate (formed when the rust reacts with the phosphoric acid).
Any porous surface, including clothing, wood, stone, etc will get
stained and such stains will never be able to be removed completely.

?? As suppled phosphoric acid was clear. I can't recollect having my
clothing or cleaning materials stained.

It turns your fingers black after a while, but it's not permanent.

No stain is permanent on the surface of skin as the cells are shed after
time, but the fact there was a stain at all is interesting. Have a look
at my reply to myself (to Chris Hogg's comment). If you've got something
rusty and phosphoric acid, it would be of interest to repeat what I had
tried3.

Not sure how it would work with a barbecue though. Phosphoric acid is
not used to remove rust. It is a rust "converter". The stuff turns the
oxide coating into a phosphate, preventing further corrosion. Whether
this would be effective on a sheet mild steel barbercue, I wouldnt
like to predict.

I would assume the ferric phosphate formed is heatproof to some extent.
I doubt it would stand up to any scraping though!

The adverts in the 70's told fibs incidentally, it does nor "turn rust
into good metal" :-)

Why am I not surprised?...

--

Jeff