Replies

1. 
   DennisS | Apr 07, 2003 07:32am | #1

   Wear eye protection, rubber gloves, and work in a well ventilated area. Muriatic acid isn't nice stuff.

   I can't answer your question whether or not soaking files in muratic acid will sharpen them or not, but I can't believe the mess & fuss trying to do so let alone the attendant dangers working with such a chemical would outweigh the cost of buying new ones.

   ...........

   Dennis in Bellevue WA

   [email protected]

2. 
   rslatm | Apr 07, 2003 03:51pm | #2

   Never heard of using muriatic acid. I've always heard of using battery acid. Supposedly you can get a few sharpenings out of this. 
3. 
   Shepherd1800 | Apr 07, 2003 04:20pm | #3

   The traditional method to sharpen files and rasps was to place them in a bucket of urine.  Many old blacksmith shops had such a bucket kept in the corner for that purpose.

   The files would rust or etch on their flats more than the points, some say a sharpened file/rasp is sharper than a new one.  It does work.

   I have used muratic and acetic acid to sharpen files.  You have to be very careful when handling these chemicals, their fumes are nasty.  If you dilute, make sure you add Acid to Water, if you do it the other way around there is a nasty reaction and explosion.

   Stephen Shepherd

   http://www.ilovewood.com

    

4. 
   SawdustSteve | Apr 07, 2003 07:17pm | #4

   Are we truely SHARPENING the files or are we just getting all the crud out from the teeth??   If I place a file into a strong enough acid, the acid will eat away at ALL the metal, including the cutting edge.  If it removes thinner metal more quickly, won't it, in reality actually round off or remove the cutting edge??   If you do try it, be sure to work outdoors and have a garden hose ready to flood (wash away) any splashes.  Safety goggles and HEAVY rubber gloves are a MUST.  Also, use plastic or glass containers as many acids will react with aluminum.   SAFETY, SAFETY, and MORE SAFETY.

   SawdustSteve

1. 
   Shepherd1800 | Apr 07, 2003 11:54pm | #5

   SawdustSteve,

   No, the crud needs to be cleaned out before the 'sharpening" process.  The acid etches or rusts the metal and apparently it etches the flats more than the edges, thereby sharpening the files and rasps.

   You can feel the difference in the files before and after sharpening.  And you are correct in using all precautions, this is not to be done in the kitchen. 

   Stephen Shepherd

1. 
   Andrew | Apr 08, 2003 04:58am | #6

   hey Steve, one more question, 2 actually. 1st, do you think I should bother diluting the acid. I'm not sure exactly how strong the stuff I have is, but it's used for cleaning stains off of my pool and is fairly corrosive (I'm not a chemist by any means though). Secondly, how long do you think I should leave the files in the acid. I'm sure this will be a function of how dull the file is and how strong the acid is, however, since I've never seen this done, I'm not sure whether you'd leave them in there for less than an hour or overnight. I'm sure there will be some trial and error here however, if you've got a rough idea that'd be great.

   Thanks

   Andrew

1. 
   Shepherd1800 | Apr 08, 2003 10:34am | #8

   You probably don't need to dilute the acid, use it full strength.  It is important that the file is clean, any metal or other debris need to be removed to insure that the acid will etch all surfaces evenly.  I clean the files or rasps with soap and water and a file card or wire brush.  I then put them in the acid and let it work. 

   The time depends on the acid and the condition of the file, do a test on your worst file first, it may take an hour it may take overnight or it may take a couple of days.

   Stephen Shepherd

1. 
   Lilshaver | Apr 09, 2003 12:57am | #9

   A possible alternative to muriatic acid is electrolysis. I etch steel using this method and it is quite safe. There is no nasty acid, only some salt water.

   Get a tub of salt water, any concentration will do. I use a plastic tub or a bucket sometimes. Connect a DC power supply, positive pole to the piece you want etched. The neg. lead goes to ground, which in this case is a piece of metal (I use copper sheeting) that is submerged in the salt water bath. Don't let the two pieces of metal touch. You could use a metal tub for the salt water and hook the neg. lead up to it directly, but then don't let the piece to be etched touch the sides or bottom of the tub. The more amps you put to it the faster the etch. Also the higher the salt concentration then the faster the etch.

   I haven't the faintest idea if this will "sharpen" a file. But it will etch metal like there's no tomorrow. I've got some old dull files, maybe I'll give it a try.

   Edited 4/8/2003 9:36:15 PM ET by jeff

5. 
   crt2cu2 | Apr 08, 2003 09:20am | #7

   Andrew,

   I have never heard of this before! Now you really have posed me a problem. Since I am a full blown dumpster diver and save all old files (for reuse as lathe tools), now I have to consider sharpening such files before finally grinding them down? Thanks a lot friend! <BIG GRIN>

   sawick