Clamps Marking Leather

[Munday]

For my first project I thought I’d make a simple folder-over knife sheath.  When I was forming it and clamped the edges with black spring clamps, I discovered some of the clamps left black marks on the leather.  I couldn’t remove the black marks so I dyed the leather.  I also discovered the clamps left dents in the leather and I don’t know if the dents can be fixed. 

I went ahead and stitched it together knowing I’d be doing it over (just to get some experience); the stitching didn’t go well either but I know more now.  

I wetted a scrap piece of leather to test the clamps. 

 

[chuck123wapati]

use contact cement. you can get weldwood brand at about any hardware store or walmart

Edited November 27, 2021 by chuck123wapati

[battlemunky]

Iron changes the composition of the leather chemically. I'm betting that the iron in the spring steel of those binder clips made it through to the leather and got you the black you see.

[tsunkasapa]

And your leather was far too wet if the clamps left those marks.

[Handstitched]

Yep, as @chuck123wapati said, contact adhesive. I've learnt my lesson when using those clamps. I only use them briefly just to hold the leather together while the adhesive sets, otherwise they will leave marks.They are an extra pair of hands in leather, but   I never keep them on for long lengths of time. Looks like your leather was a bit too wet. 

HS

[HandyDave]

When i do have to clamp something and leave it for a time. I put some scrap  strips of leather between my clamps and my finished piece. And i also have seen similar clamps that look rubber coated that might work better without the problem. The scrap leather under clamps also helps spread out the load enough to not indent if leather is a little wetterthen it needs to be.

[fredk]

I use either scraps of leather or pieces of lolly sticks between the bulldog clamps and the leather. Which I use depends on a: what come to hand or b: the shape of the glued line

Lolly sticks spread the clamping load better and leather will conform to a curve better

I've left things clamped up like this for days or weeks, not usually deliberately but because I've forgotten to finish the item or I've been waiting on something to finish it off

[Munday]

Thanks for the information.

[fredk]

You see your knife sheath there? If you clamp it up with lengths of lolly (popsicle?) stick along the shape you can get a nice sharp line along the blade edge

[jcuk]

These maybe of use to you also 18mm are available in some places. Things like that i usually lightly tack but each to their own.

https://www.artisanleathersupply.com/products/locking-pins

Hope this helps

JCUK

[fredk]

A cheaper alternative to those fancy pins is a mapping pin into a small block of cork

[zuludog]

Besides all the previous comments, your clamps are too strong and have too narrow a surface area. Have a look at this video. You can see that Ian has used less powerful clamps, and also wrapped them in thinner leather to cushion them 

Or you could try clothes pegs/clothes pins

But there's something I do -- the plastic clothes hangers for ladies' skirts often have clips or clamps on them to hold the skirt, and those clamps have a larger surface area; I just saw them off with a junior hacksaw, and use those

Making a Leather Knife Sheath - YouTube 

Edited November 28, 2021 by zuludog

[chuck123wapati]

I don't use clamps on leather that's what contact cement is for, glue it, hammer it then i sew it up and its clamped for good.

[chuck123wapati]

7 minutes ago, zuludog said:

Besides all the previous comments, your clamps are too strong. Have a look at this video. You can see that Ian has used less powerful clamps, and also wrapped them in thinner leather to cushion them 

Making a Leather Knife Sheath - YouTube 

man he is good with that awl !

[zuludog]

1 minute ago, chuck123wapati said:

man he is good with that awl !

We're in danger of going OT here, but yes, he is; also watch videos by JH Leather. She uses pricking iron  + awl for most of her sewing, and she's excellent. IMO her video on doing the saddle stitch is one of the best

[JayEhl]

In the most recent issue of leather crafters Leather Crafters and Saddlers Journal an article was written about how you can easily take apart those office binders and taking some scrap leather that's long enough to wrap the inside of the clamp, punching a couple of holes for the levers (or whatever you want to call it) and put it back together.  I've made a bin of different sizes of these.  Works great.   
I also found this on the omnicientweb:    https://www.instructables.com/Leather-Workshop-Binder-Clips-two-Minutes-Hack/

 

[Hardrada]

There are clamps that are non-marring. Irwin Quick-Grip come to mind.

The only time I use bulldog clamps is when I'm wet-moulding and the stitch line will go right along and over the marks left by the clamps.

Some time ago someone from Japan joined the forum and his YT channel had a tutorial on how to make leather covered bulldog clamp jaws, to prevent this problem, but I didn't bookmark the video, alas.

___________

Hah! What you know... I found it.

 

Edited November 29, 2021 by Hardrada