Quote:
Originally Posted by T-Cut
Chemical type rust removers are usually based on inhibited phosphoric acid. The inhibitor prevents the acid from attacking fresh metal after the rust has been removed/converted to ferric phosphate and such. The acid is certainly not dilute or weak. In fact it's typically around 80% concentrated, so not to be messed with. It will take your eyes out if they get splashed (so wear goggles and neoprene gloves).
As to whether it would attack a clean piston bore in a rusty caliper, I suspect not. Not to any extent that would affect its operation. The metal surface may stain/blacken, but it shouldn't be etched. The product referred to in the above link is only 45% strength, so weaker than the industrial rust removers my old company made, but it should be suitable. Basically follow the instructions to the letter.
An impressive alternative to acids is the electrolytic method which does quite amazing things and in many ways is preferable to chemicals.
There are a few threads here on using a car battery and bucket for de-rusting parts. You can also find videos on YouTube.
EDIT: YouTube videos: https://www.youtube.com/results?sear...c+rust+removal
TC |
I've used the 45% stuff in the Amazon link and it works well if left for 18-24hrs. Not very economic for larger parts (@ £20 for 5L) but a caliper 'should' (?) fit inside a cut-off 6 pint milk thingy, with maybe 3 litres of acid.
I've seen/read about the electrolytic method before but never tried it. Maybe I'll give it a go with a caliper in a milk carton.
Quote:
Originally Posted by Odd Job
For mild rust removal I've used normal vinegar, also for carbon removal on inlet / exhaust valves.
It takes a while to work on the item, but it wont kill you / poison you and is a lot more forgiving than some other products which can cause pitting if left too long.
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I've tried white vinegar and it does work well - slower than acid but cheaper, £10 for 5L
here.