Copper Rivets Coated with Pitch?

[TomE]

I am repairing a heavy surcingle and the copper rivets appear to be coated in a pitch-like substance.  As I ground off the tip of a rivet with a Dremel tool a black, tarry liquid oozed from underneath the burr.  The tar is solid a room temperature.  I haven't found any mention of using pitch in the harness making books I have, or from a Google search.  I am interested in why this would be done, and the type of pitch/tar used in saddlery/harness work.  Thanks for the information. 

[Mulesaw]

45 minutes ago, TomE said:

I am repairing a heavy surcingle and the copper rivets appear to be coated in a pitch-like substance.  As I ground off the tip of a rivet with a Dremel tool a black, tarry liquid oozed from underneath the burr.  The tar is solid a room temperature.  I haven't found any mention of using pitch in the harness making books I have, or from a Google search.  I am interested in why this would be done, and the type of pitch/tar used in saddlery/harness work.  Thanks for the information. 

Very interesting.

My initial thought is that it was done to waterproof it. In the 2nd book of the "little house on the prairie" series (I think it is called farm boy in English), Almanzo's family get a visit form an itinerant shoemaker. He uses some tar to impregnate the sewing thread to waterproof it. But then again there is a difference between a rivet and a stitching.

I'll try to look in the old German book when I get home, to see if there is any mentioning on pitch/tar.

Brgds Jonas

[chuck123wapati]

i think its to keep the copper from turning the leather green.

 

[TomE]

50 minutes ago, Mulesaw said:

Very interesting.

My initial thought is that it was done to waterproof it. In the 2nd book of the "little house on the prairie" series (I think it is called farm boy in English), Almanzo's family get a visit form an itinerant shoemaker. He uses some tar to impregnate the sewing thread to waterproof it. But then again there is a difference between a rivet and a stitching.

I'll try to look in the old German book when I get home, to see if there is any mentioning on pitch/tar.

Brgds Jonas

Thanks, Jonas. I am using a cobbler’s wax (pine resin + beeswax) for the thread. This is black nasty looking stuff. Come to think of it the decaying linen thread is coated with something dark, which I had assumed was accumulated dirt. Thanks for checking your sources. 

23 minutes ago, chuck123wapati said:

i think its to keep the copper from turning the leather green.

 

Thanks, Chuck. That’s a neat idea. Seems unlikely to make the rivet more secure so I was stumped. I made a shoeing apron out of chrome tanned apron split and had wondered if the copper rivets would discolor the leather. The pitch would be too messy for that project.  This surcingle is 1-2 layers of 11-12 oz leather dyed dark chocolate brown, almost black. 

[Mulesaw]

@TomE

Hi Tom, I just got back to the ship today, and while I was at home, I looked in the old German saddler book regarding the use of pitch/tar on rivets - but I couldn't find anything mentioned about it. 

My best guess is still that it was done for some sort of water proofing. I have seen some old leather gear that was made using iron rivets and iron buckles etc. They often tend to get damaged when those things start to rust. So perhaps the original maker of the surcingle wanted to make sure that it didn't happen even though he/she used copper rivets. I think that if you used iron/steel rivets, coating with tar would effectively seal all the "end grain" in the holes that you punched to insert the rivet. 

But is is still puzzling.

Brgds Jonas