Ink Removal from dried leather

I have a problem that I am having a little bit of difficulty in solving, and I thought perhaps that someone with your expertise with tools and abrasives might be able to help me solve. I need to try and grind/sand ink off of a 24 sq in surface, and I have 10,000-12,000 to do.

I have some flat panels of white dried leather 4 inches by 6 inches(about 110mm by 160 mm) by 1.5-2.0 mm thick. The dried leather is very tough, a lot like wood except that you can bend it a little. I got them from Thailand in the past, but they are becoming more difficult to find, so we thought we could try and remove the ink and re use them. (most are just what we call mis-prints. We make post cards out of them. The dried ink is fairly tough to remove. We cannot use any solvents to get the ink off, as it would wreck the leather. We have tried a belt sander and sand blasting. Both were able to remove the ink, but took so long that our labor cost was more than the value of the blank piece. We tried using a 4 inch bench planer, but it was way too aggressive and fairly dangerous. We have also tried coarse grinding wheels without much success. Our goal would be to clean each piece (approx 24 sq in) in 30 seconds or less. That would allow us to do approximately 120 pieces per hour, since we have thousands that need to be cleaned. I have attached 3 pictures to get an idea of what I am talking about. I need to get the proper tool to do this or build something from scratch that would do the job.

Thank you for your time

Steve

Lots of different inks out there ... some are water soluble but most permanent inks require a solvent ... I would try a good carb or brake cleaner on a small piece. If it works you will have to spray vigorously while holding the leather so the solvent runs off ...if you lay it down the solvent will allow the diluted ink to seep into the leather.
When you are finished wash the leather in cold water and dish detergent then rinse.
Of course you do this at your own risk but I think it will work OK

Have you tried a widebelt sander ("Timesavers"), or perhaps one on the plan of a Super Olympia which is sort of a widebelt jointer, with powered feed rolls over top?

A "typical" widebelt won't feed your parts well because they are too short. But there are single drum machines with no platen that might have the rolls close enough.

I'm not sure on the Super Olympia, will have to measure between the rolls tomorrow. But I think it would do a smooth job.

AQ wide belt would do about 120 pieces/minute. A Super Olympia could do them almost as fast as you could manually place & start them under the feed rolls but is limited by the 13" width of belt.

PS, it is a site requirement that you put your location (USA is not enough) in the heading; and it often helps people understand better how to help you.

smt

RE: Solvent use

cncfixxer said:

Lots of different inks out there ... some are water soluble but most permanent inks require a solvent ... I would try a good carb or brake cleaner on a small piece. If it works you will have to spray vigorously while holding the leather so the solvent runs off ...if you lay it down the solvent will allow the diluted ink to seep into the leather.
When you are finished wash the leather in cold water and dish detergent then rinse.
Of course you do this at your own risk but I think it will work OK

Click to expand...

I cannot use solvents on the dried leather, it makes it warp. The ink has to be removed by mechanical means only.

Stephen,

Thanks for your reply. I do not have any experience with the equipment you referenced so any additional information would help. I did try a 6 inch by 36 inch belt sander with 36 grit sandpaper. That took the ink off in about 1 min 30 seconds which was too long for us. I live in California, Palm Desert area so our warehouse is about 105-115 this time of the year. I have large fans but I am trying to find a way to make the process of cleaning the parts faster. We can also hook up a room a/c nearby as well. Obviously with 10,000+ pieces to do the faster the better.

Steve

steve9303 said:

Stephen,

Thanks for your reply. I do not have any experience with the equipment you referenced so any additional information would help. I did try a 6 inch by 36 inch belt sander with 36 grit sandpaper. That took the ink off in about 1 min 30 seconds which was too long for us. I live in California, Palm Desert area so our warehouse is about 105-115 this time of the year. I have large fans but I am trying to find a way to make the process of cleaning the parts faster. We can also hook up a room a/c nearby as well. Obviously with 10,000+ pieces to do the faster the better.

Steve

Click to expand...

Timesavers are sort of like wide belt sanders with automatic infeed. You find them in industrial woodworking shops. Used for doing things like leveling out tabletops in one pass. I know where there is one in Watsonville, CA, but that's a bit of a hike for you. The good news (from your point of view) is that they tend to run finer belts than 36grit. 120 grit might give you a half-way usable surface. I might call around to the local woodworking shops to see if they know anybody local who has one. Metal shops use them too, but tend to call them "Grainers". You probably don't want to run your leather in a grainer that's been running aluminum. Loaded up with Al dust, which will mark your leather.

As somebody above mentioned, there are a couple of styles of timesaver. One version has two belts (coarse and fine) and gets them both done in one go, and the other just has one belt. You want a single belt machine if you can find one. The two belter probably won't feed your short little pieces without them being on some sort of a carrier plate. They'll get stuck between the two belts. You can run your parts on a carrier plate, but that's a pain. Anything beyond this, you really need to talk with whoever owns the machine, and see how (if) they want to tackle the problem.

FWIW,
Brian

Once I had dykem on my hands and used go joe abrasice goo to clean up. It probably would hurt your leather though.

24 sq.. 4”x 6” one side? 10 or 12k parts. Seems the belt sander a good choice but no way to hold the parts and too much surface contact?
Could you use the belt sander roller end for less contact surface area and the part on a flat surface bumped to a shoulder or held on on a vacuum chuck. (glue-on might work but time consuming) 10 or 12 K parts so spending a few bucks to fabricate a system would seem worth the effort.

I will not... but I believe could make an angle fixture to hold the belt sander roller end over the table of my TC or my surface grinder with a vacuum chuck on the table and run the parts. The roller end would act like a 6" (or so wide) grinding wheel and would be self cleaning to stay sharp grinding leather.

RE: Fabrication of a part to remove ink

michiganbuck said:

24 sq.. 4”x 6” one side? 10 or 12k parts. Seems the belt sander a good choice but no way to hold the parts and too much surface contact?
Could you use the belt sander roller end for less contact surface area and the part on a flat surface bumped to a shoulder or held on on a vacuum chuck. (glue-on might work but time consuming) 10 or 12 K parts so spending a few bucks to fabricate a system would seem worth the effort.

I will not... but I believe could make an angle fixture to hold the belt sander roller end over the table of my TC or my surface grinder with a vacuum chuck on the table and run the parts. The roller end would act like a 6" (or so wide) grinding wheel and would be self cleaning to stay sharp grinding leather.

Click to expand...

michiiganbuck: The 4 ' by 6 " area is one side. So the 24 sq in to be cleaned are all on one side. We think the number to be cleaned is 10-12K but it could go as high as 20K pcs.
When I used my 6 inch belt sander I was using just the end. When I tried to put the entire palnel on the flat part of the belt there appears to be too much surface area contact to get any decent removal of the ink. When I use the curved end I have better control of the surface area and can get better removal of the ink. That process still takes too long (90 seconds or so per pc) Also when I put too much pressure on the piece against the curved portion of the belt it makes the belt stop. I was hoping to figure out a more aggressive means to removing the ink. I saw where someone wanted to make there own mechanical apple peeler and they made there own wood cylinder and then drilled screws into it just leaving the heads exposed, so as it turned the screw heads acted as the removal device of the peel. I tried to think of different ways to mimic that action. I don't know if it is possible but I thought could you take a bench grinder and make a custom wheel with maybe pieces of hack saw blades with just the teeth barely exposed. Also I tried to think of a way something like that could be used in a drill press with a slower speed that might be a more controllable situation. The reason I mentioned hack saw blades is that when I took a small hack saw and tried it on the surface it seemed to be a type of abrasive action that night remove the ink quicker. I do know if a band saw could be reconfigured to do something like that. It's like a need a cylinder(similar to the end of the 6 in belt sander), with a more aggressive surface. Obviously it doesn't have to be 6 inches. Even if I had something 2" wide we could make 2-3 passes and it would be good. I could always finish each piece with a final sanding on the belt sander to finish any imperfections.

Good we agree on using the curved end. Belt stop… or motor stalled?
If the motor stalled but the process worked then a more powerful belt sander might be the ticket.
90 seconds might turn to 60… perhaps less.
12k parts perhaps worth 2 or $3 as blanks are worth buying a serious belt sander if that is what you need..
Jet ¾ hp 6x48” belt sander a little over a grand. Might find a good used machine for $500 or so.
Harbor Freight 1 HP machine now on sale for $200. Hard to imagine stalling a 3/4 or 1 HP motor.
Perhaps you have such a machine as you mention 6" sander and most I see are 3/4 HP or better .

Might try a wood jointer or planner

Splitter?

it just occurred to me: what about a splitter?

Splitters are leatherworking tools used to 'split' raw hides into leather sheets of various thickness. Basically, they're flat knives held "X" distance above an adjustable roller. Feed the hide in, and it comes out as two hides, one of thickness "X", and one as the rest. The big ones will split an entire hide down in seconds. I know there are desktop versions available.
The little ones sound like they'd be more what you need. Or a skiver. (Google "Leather Splitter" and/or "Leather Skiver".)

Siegel's leather supply in Buelton, CA used to stock the desktop splitters. Don't know if they still do or not. (www.siegelofca.com)

FWIW,
Brian

HP of belt sander

michiganbuck said:

Good we agree on using the curved end. Belt stop… or motor stalled?
If the motor stalled but the process worked then a more powerful belt sander might be the ticket.
90 seconds might turn to 60… perhaps less.
12k parts perhaps worth 2 or $3 as blanks are worth buying a serious belt sander if that is what you need..
Jet ¾ hp 6x48” belt sander a little over a grand. Might find a good used machine for $500 or so.
Harbor Freight 1 HP machine now on sale for $200. Hard to imagine stalling a 3/4 or 1 HP motor.
Perhaps you have such a machine as you mention 6" sander and most I see are 3/4 HP or better .

Click to expand...

michiganbuck: Sorry for delay in answering I was away for a few days. To answer your questions I went and looked at the unit as I purchased it used and I wasn't sure.
The labels on the equipment and motor say "Central Machinery 6 inch belt/ 9" Disc Sander. sku T6852, 1 HP motor, 12 amps, 3450 rpm. I was trying to sand with a Z24 resin bond., and I think the entire length of the sandpaper is 48 inches. When I used force to sand the pieces the sandpaper stopped but so did the round end piece at the end. I looked around to the side and the motor was still spinning as well as the disc sander. I tried it 6-7 times and each time I was able to stop the belt and the end piece but the motor and disc sander kept going. It's a used unit so I am not sure what I should ticker with to change any of the parameters.

Brian,

Thanks for reply, info and reference. I will definitely check out those options.
Steve

Know any one with wood shop to try a planner?

RE: Wood Shop

michiganbuck said:

Know any one with wood shop to try a planner?

Click to expand...

Michiganbuck: I'll definitely look for someone with a wood shop to try some of the equipment out before making a purchase. We live in kind of a retirement area so there isn't much industry at all. But there may be 1-2 cabinet guys here that might have some equipment to help me do the testing. Thanks

Steve

High school wood shop might be a chance to also try.

Re: The planer

michiganbuck said:

High school wood shop might be a chance to also try.

Click to expand...

Regarding the trial of the planer: Is there a safe or proper way to decrease the rpms of those units? I know they make dimmers for lights but I have no idea if you can do that to a motor that is set up for 1 speed. I don't want to wreck it. I think if I could vary the speed it might be more easy to work with. Any ideas?

Thanks