This stuff is a big improvement on phosphoric acid because it dissolves rust
but not metal, but it's really pricey. They push it as good value because
your 500ml at £24 makes 20 Liters, but it doesn't take much surface area of
metal to deplete it. There isn't a generic name for this modern type of rust
remover so it's hard to Google up alternatives, so:
Are there any similar but cheaper products out there?
The electroplating professionals use inhibited hydrochloric acid to
pickle steel.Leaves it clean and greyish.It also attacks the oxides
but leaves the base metal alone.It has to be flushed off,preferably
with an alkali solution to neutralise it after the process,then the
parts must be protected immediately as they will go red straight away.
I have been using brick and concrete cleaner from the local builder
merchants, read the label it needs to say 90% hydrochloric acid or
similar if it says green or less than 10% ear of bat, 10% tongue of
newt then don't waste your money.
I bought it mainly for descaling black plate prior to machining but I
have dropped some very corroded thread cutting taps into it just to
see what they came out like.
The came out matt grey as Mark says and given the state of the
original taps they came out brilliant, they even had a sharp edge,
whether this was etched by the acid I don't know.
Costs about £7 a gallon where I go.
Only really suitable for items you can immerse in a bucket, but I've
had excellent results using electrolytic rust removal. The process
only remove rust, not base metal. Just needs a suitable power supply
(I use a 12v/4amp battery charger), and a sprinkle of washing soda.
I looked at that comment and thought Mike had failed to mention that the
washing soda was added to water so I can see the sense in Marks comment.
Personally I've used electrolytic de-rusting on a number of items and am
a fan. IIRC if using a battery charger it requires a dumb one as
apparently the intelligent ones will just shut down and wont work for
this purpose. Mine is a bit thick as it is quite happy in that use and
not aware of no battery. Plenty of information out there such as
3 other bookmarked links are now dead so a new search for further
information may be required.
Ive just bought some Bilt Hamber de-ox gel (they also do crystals to
mix with water) when I was ordering some other (car related) stuff.
Not used it yet so cant give first hand results, but have some bits to
do over weekend.
Thanks. I like the sound of the electrolytic process. Hydrochloric - does it
really only dissolve the rust and not the metal?
Later today I managed to find some other products that seem similar to the
Shield Technology product. One is Evapo-Rust and another Expro-32. I've
ordered some of the latter and I'll report back if it impresses me.
Evapo-Rust sounds interesting. According to the description it should be
able to dissolve a lot of rust before it's depleted, but I'd already ordered
the Expro-32, so maybe I'll get that another time...
I wonder if the high price of this stuff is a consequence of the ingredients
being expensive or the recipe being secret? I read about the chelating
agent - do you know what the other ingredients are?
I seem to recall some vague information on the manufacturers website, though
I have forgotten precisely what it was. Evaporust is expensive at £36 per US
gallon, but I regard it as a small price to pay for an effective product
that does no harm to me, the environment, or the customers work.
An old trick is to use household white vinegar. Use enough to
*completely* immerse the rusted object. Once the vinegar is in the
plastic pail, start mixing in normal table salt until no more will
dissolve. Keep stirring and adding salt until you know for sure that
saturation has been achieved. It may take a pound or more of salt per
container of vinegar.
Now, immerse object in the mixture. Make SURE the object is completely
immersed, or you will get a line across the metal where the surface was
and you will NEVER get rid of it.
Check every few hours until all the rust is gone. Heavy rust may take an
The liquid is reusable, depending on how much rust has been removed and
may safely be dumped in a discrete corner when used up.
Try it. It's cheap and removes rust ONLY. It's all I use.
It is the hugely destructive effects of people playing with acids that they
don't understand, that have driven the market for safer non-destructive
alternatives, which is precisely where this thread started. I suggest, as a
chemist most of my life, that people properly research the effects of acids
on metals before being tempted to use the discredited technique mentioned
Whilst I would agree that it is perhaps unwise to encourage the
uninitiated to start using strong acids like sulphuric, hydrochloric*,
or nitric*. I think you are perhaps taking paranoia to extremes when you
extend such a warning to the use of household vinegar.
Note Mike was not even recommending the use of glacial (100%) acetic
acid, which can be damaging to fabric if not washed of, and moderately
irritating to the skin. Household vinegar is typically 5-8% acetic acid.
I don't know why you describe the above technique as "discredited"; I
have not tried it and can't comment from experience, but I am interested
to hear why you make the claim. Personally, I would provisionally assume
that if Mike says he has tried it and it works, that he was telling the
truth unless I had some strong evidence to the contrary. You seem to
have this, so please enlighten us.
*I'd be very reluctant to have hydrochloric acid in my workshop - not
because of its hazard as a liquid (which is high, but manageable to the
trained), but because HCl is a gas, and the acid, about 36% aqueous
solution of HCl, gives off the gas and will corrode most metals within a
pretty wide radius. Enough will leak out of most containers to do this.
Nitric acid is similar. Sulphuric acid, though extremely dangerous if
you don't know how to handle it, does not give off corrosive vapours
I wish certain people would just find a few rusty bolts, washers and
nuts. Then they could actually spend the cost of a few cups of coffee
and buy salt and vinegar.
It's an easy enough process to try out and other than the smell of
vinegar, has no bad side effects.
The last item I cleaned with this method was a badly rusted pair of
needle nose pliers. After an overnight soak, they came out rust free.
There WERE small pits in the metal where the rust had worked it's way in.
I should have mentioned that immediately after removal from the bath,
the item(s) should be immediately rinsed with clean water and then dried.
The critics of this method have obviously never tried it. Their loss.
My experience with acid based rust removers is that they leave the metal in
a highly reactive (dark colour and 'metallic smell') state that rusts just
from being rinsed. One of the best features I found of 'Restore Rust
Remover' was that it not only dissolved just the rust, but after a light
scrubbing you were back to fairly passive bright steel. After scrubbing it
recommended dipping back in the solution and wiping dry, which would make it
even more passive. I think it was excellent, but about 10 times too
Has anyone else used 'Restore' and compared it to other products?
David. It's not the potential for personal injury I referred to, any fool
who plays with acids without learning of their hazards deserves whatever
injuries he gets. No, it was the damage to the metal I referred to.
Penetration of the hydrogen ion into the crystal structure of the metal
leads to long term degradation and frequently creates nodes on which future
rusting is accelerated. That is just the effect on steel when only one metal
is involved. Composite articles containing two or more metals will also
suffer various electrolytic effects which will exacerbate the damage.
You have to ask yourself why institutions like ship builders and navies the
world over, who jointly probably have the biggest and most damaging problem
with rusting steel, spend fortunes on complex rust treatments if was as
simple as dipping in a vat of salt and vinegar!
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