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Miken
Joined: 24 Dec 2012 Posts: 544
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Posted: Tue Sep 11, 2018 7:39 pm Post subject: Phosphoric acid |
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I know this has been discussed before but I would like a few points clarifying please.
I wish to purchase some phosphoric acid to treat steel before painting. Maybe to remove very light rust.
On eBay you can get it from 30% to 85%.
So, 3 questions:
a)Which is the most suitable strength for home use?
b) When it is applied do you wait until it dries on the work or wipe it off while it is still wet?
C) wet or dry, do you wash it off with water or not?
Thanks, Mike. |
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ukdave2002
Joined: 23 Nov 2007 Posts: 4109 Location: South Cheshire
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Posted: Tue Sep 11, 2018 10:39 pm Post subject: |
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30/40% is what's normally used, leave it on for 30 mins treat all the steel even if it looks rust free, rinse off, then clean the panel with panel wipe (this ensures all moisture is removed as well as cleaning the panel) paint straight away.
Dave |
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Kleftiwallah
Joined: 27 Oct 2016 Posts: 222 Location: North Wiltshire
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Posted: Wed Sep 12, 2018 9:45 am Post subject: |
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And don't ever let the acid even see aluminium!
Cheers, Tony. _________________ It may work in practice, but not necessarily in theory! |
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Miken
Joined: 24 Dec 2012 Posts: 544
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Posted: Wed Sep 12, 2018 12:09 pm Post subject: |
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Thanks for the reply.
After 30 minutes i expect it will have dried off.
So should I re-apply the acid before rinsing off?
Maybe it makes no difference?
MN |
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Bitumen Boy
Joined: 26 Jan 2012 Posts: 1735 Location: Above the snow line in old Monmouthshire
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Posted: Wed Sep 12, 2018 8:37 pm Post subject: |
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Miken wrote: | Thanks for the reply.
After 30 minutes i expect it will have dried off.
So should I re-apply the acid before rinsing off?
Maybe it makes no difference?
MN |
I think it's best not to let it dry out if possible. On a vertical panel one of the best ways of applying the acid that I've found is to use tissue paper - loo roll or blue shop towel is fine. Lay the paper on the panel then apply the acid. If it dries out reapply to keep it wet and working, I don't think it does anything if it dries out. |
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Miken
Joined: 24 Dec 2012 Posts: 544
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Posted: Wed Sep 12, 2018 10:13 pm Post subject: |
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Ok, thanks |
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