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Cleaning a file

#1

Hello folks, I have another rather simple question. As many of you
know, I seem to be a copper freak. One of my favorite files is a 6"
Swiss made #4 cut half round file. It gets used a lot. I’ve tried to
clean it with a file card and a stainless steel toothbrush (serious
hygeine) and am still only having moderate success cleaning it out.
I’ve read in the past that files can be cleaned or possibly
sharpened even by dipping them in some acid mixture. I don’t
remember what acids were used but I have another idea to clean my
file and I’d appreciate opinions. I think it’ll work well but I
value your advice. I’m thinking of dipping it into the ferric
chloride solution I use for etching copper on occasion. I know it’ll
get rid of the copper nicely and I don’t forsee any damage to the
file. Ferric chloride, as I understand it, is a salt resulting from
cleaning steel with hydrochloric acid. Seems to me it’d be ideal for
this application but I’ll wait to see what y’all have to say about
it. I like my little file and don’t want to ruin it. Thanks in
advance, you folks are great!

Mike

#2

Make yourself a scraper from a piece of scrap brass a bout 15-20 mm
wide. Rub the end of this strip across the file parallel to the
teeth. The file will wear grooves in the end of your scraper which
makes the job easier. I was taught to do the same thing using the
edge of a coin.

It is a good idea to rub chalk into the file before you use it as
this prevents soft metals, like copper, sticking in the file teeth.

Bill Bedford

#3

Hi, Mike, You said it yourself:

cleaning steel with hydrochloric acid."

So, hydrochloric acid cleans steel. I can tell you from experience,
it not only cleans it, it etches it. That’s hydrochloric acid,
a.k.a. pickle. If it’s old pickle (or, I suppose, if your files are
very clogged with copper) the file will end up pinkish, but it will
be nice and sharp after a few minutes bubbling away in pickle.

I’d like to add a caveat: do it with good ventilation. You do NOT
want a snootfull of those fumes, I promise.

HTH! --Noel

#4

Hello Mike, Ferric chloride will take away a little bit of your file.
But is not so bad it will make your file as new sharp again. But clan
the file very good afterwards or better neutralize with a washing
soda solution.

But why don’t you use hard chrome plated files. I use them for
titanium. They will not clock up and last 4 times longer than normal
files.

Martin Niemeijer
N design
compositions in precious metal
Rieteweg 10
8041 AK, Zwolle
Netherlands
info@ndesign.nl; www.ndesign.nl

#5

Greetings,

When I file non-ferrous materials I rub a bit of chalk, the black
board type, over the file before using. It doesn’t keep the file
teeth from clogging but they can easily be cleaned with a few swipes
with a file card.

Hope this helps.

#6

Noel,

It is unusual to use hydrochloric acid as pickle most pickle is
based on sulfuric acid or a close relative like sodium bisulfate.
With that being said sulfuric acid and sodium bisulfate will both
etch steel as you noted. There is at least one commercial service
that “re-sharpens” files by using an acid bath.

Jim Binnion

James Binnion Metal Arts
Phone (360) 756-6550
Toll Free (877) 408 7287
Fax (360) 756-2160


@James_Binnion
Member of the Better Business Bureau

#7

When I ran a trade shop some years back I was pressed for time and
looking for experienced help. I had an applicant who told me that
she had had 4 years of experience at the bench before she came to
me. I decided to let her have a try.

After demonstrating her “experience” by blowing stones out of pieces
that should never have been subjected to steam without tightening,
melting countless heads and ring shanks, (that was because of the
torch - she said:) and destroying a few chains - she began to
complain that the files were not sharp enough to remove material as
quickly as she wanted. I told her to go get a file card off my
bench and see if cleaning would help. When she returned with a 3" x
5" card and a puzzled look on her face, I realized that it was time
to interview the next applicant…

Whoever supposedly gave her her training cost me well over $1,000…

Brian Marshall

#8

Hi Have you tried gun cleaning solvent? sporting goods should have
it.

Dwight McCartney
watchmaker

#9

I could never stand the idea of using a file card or wire brush with
steel wires to clean steel files. Instead I have found a brass wire
brush which works just as well. But to really clean a file I’ll go
through it quickly groove by groove with a pointed brass pick. Makes
a good “mindless activity” to do before getting into the creative
stuff.

Jill
http://www.jjewelry.com

#10 
It is unusual to use hydrochloric acid as pickle most pickle is
based on sulfuric acid or a close relative like sodium bisulfate.
With that being said sulfuric acid and sodium bisulfate will both
etch steel as you noted.

OOps! Of course you are right, Jim. Color my face red. Not a slip of
the tongue, but a slip of the brain. The good news is, etching a
file with pickle will sharpen it. The bad news is, I have trouble
keeping my acid names straight.

Thanks also for the gentle way in which you set me straight.

Noel

#11

Looks like it’s just Bill Bedford and me who use a home made method
to clean files. Bill uses brass and I use a 5mm strip of gilding
metal (mostly copper). A 100mm long strip with one end coiled up to
be nicer for your palm, and dig the file clean. Steel file cards just
wear the files down, it seems to me.

Brian

B r i a n A d a m
e y e g l a s s e s j e w e l l e r y
Auckland NEW ZEALAND
www.adam.co.nz

#12

Just for the record, file carding has damaged more files than
enough. While it will fetch metal out of the teeth if used roughly
enough, it also dulls the teeth as the wires are often harder than
the file. The correct way to clean any file is, as has already been
mentioned, by using a piece of soft metal - copper, brass or a small
coin, and pushing the edge of this across the file holding it nearly
upright and at right angles to the cutting edges of the teeth. This
soft metal will quickly form serrations on its edge which exactly
match the shape of the file teeth and will clean out under the teeth
without damaging or reducing the life of a file. For a double cut
file you should repeat the procedure for each set of teeth as the
upcut and overcut are both different pitches. Its a good habit to
clean the most used files every week or so this way to keep them in
good condition. Any cutting tool which is not in tip-top condition
will produce inferior work and harder work and more frustration for
you.

Best Wishes, Ian

Ian W. Wright
Sheffield UK

#13

Continue from:
https://orchid.ganoksin.com/t/cleaning-a-file

I accessed your website and found helpful on cleaning
small, fine files used for boat modelling. Thank you.

I used the following procedure which produced outstanding results so
thought I’d share this with you. For safety reasons I
decided not to utilise nitric acid or dilute sulphuric acid. Instead
I used battery acid 12/50 undiluted and soaked the files in this
solution for one hour. The files were then removed and washed off in
clean water.Next I soaked them in a strong solution of Baking Soda &
Water ( approx. 2 tablespoons to 1/2 litre water ). They were left
in this solution for one hour. I then rinsed them again in clean
water and noted oxidation (rusting) started to occur! To counter
this I then placed the files in a solution of oxalic acid ( mixed
1:10)and left them for one hour. I then removed them from this
solution and left them to air dry. ( important - do not rinse
solution

Kind regards
Peter.

#14

Hi Peter,

Another method of resharpening files that I have had some success
with is to just clean in an ultrasonic, rinse or steam and then
immerse in plain vinagar for 12-24 hrs checking occasionaly as the
etch progresses.

Regards, Jeffrey

#15

Hello all

File etsching can be done with several types of accid, howevere they
al do not etch in the deep en some sollutions eat away the highest
points of the teeth

For carbon steel the following sollution works perfect and fast

Clean the file in a hot washing soda bath with a brush, or use an
other way of decreasing.

Than put them in the following mixture:

7 parts water
3 parts sulphuric acid (H2SO4)
1 part Nitric acid. (HNO3)

In a few minutes ready. Neutralize in washing soda again.

Works also very good on Burrs
Greetings
Martin Niemeijer

Ndesign
Cultuurwerkplaats R10
Rieteweg 10
8041 AK, Zwolle
The Netherlands
info@ndesign.nl ;www.ndesign.nl
Phone +31 (0)38 7501258
Mobile phone +31 (0)651831576

#16 
Clean the file in a hot washing soda bath with a brush, or use an
other way of decreasing. Than put them in the following mixture: 7
parts water 3 parts sulphuric acid (H2SO4) 1 part Nitric acid.
(HNO3) In a few minutes ready. Neutralize in washing soda again.

How important is the degreasing to prevent the formation of
explosives? I’m not sure of the concentrations involved but know
that nitric acid and sulphuric acid together are the basis for
making explosives from many organic materials. Nitroglycerine, TNT,
Nitrocellulose etc. The diprotic sulphuric acid gives the nitric
the oomph it needs to react with the organics. Would contamination
with lubricants, etc be a risk at these concentrations of acid?

Howard Woods
Eagle Idaho

#17

Hello Howard,

The degreasing has nothing to do with preventing explosives.
Therefore the amount of crease is not enough on a file.

The acids are strong enough to do there own decreasing. However the
reason is, that you want to etch the surface of your rather expensive
file very even. If the files are greased or otherwise dirty, parts
the acid will react later to the dirty steel than the clean parts.
The teeth of the file will not be of the same height after etching.
The mixture I gave was from a book of 1936. And even I heard that
this mixture goes back to the 19e century.

It has an deep etching effect on carbon steels. It eats the metal
also very good in the grooves. I have tried other mixtures and acids,
they will work, but this is fast and effective. And some mixtures
only eat the top of the teeth away, and that is not what we want.

Be aware, the amount of acids is based on 100% strength. And need to
be upgraded if you have less stronger acids. Less use of water. It is
dangerous to work with HNO3 stronger than 60%. Stronger will fume and
even react with water vapour.

But strong acids are nothing for the ignorant among us. When you
mix, take safety precautions and always first water than add the
acid. And always mix slowly.

Greetings
Martin Niemeijer
Ndesign
Cultuurwerkplaats R10
Rieteweg 10
8041 AK, Zwolle
The Netherlands
info@ndesign.nl ;www.ndesign.nl
Phone +31 (0)38 7501258
Mobile phone +31 (0)651831576

#18

Hello Howard;

There would be no problem with producing an explosive with the 7:3
parts water to sulfuric acid plus 1 part nitric acid mixture and a
hydrocarbon grease. You could, of course, get in trouble by pouring
the water into the sulfuric acid rather than the other way around. It
is important to pour the acid into the water slowly with good mixing
and plenty of cooling. A lot of heat is liberated! The types of
explosives you list are made by nitrating compounds that have
hydroxyl groups (i.e.: alcohol group, -OH). The acids used are red
fuming nitric acid and Oleum (fuming sulfuric acid). Water is
liberated when the nitric acid reacts with the hydroxyl group. The
fuming sulfuric acid contains sulfur trioxide which reacts with the
water formed to produce more sulfuric acid. Nitration will not
proceed to any extent in the presence of water.

Captain Blood
"Marlinespike Seamanship in Precious Metals"
@Alden_Glenda_Blood