Basic question about glueing and stitching

[NeilMott]

Hey all.

This is probably a super-basic question about glueing and stitching, but I can't seem to find it anywhere.  I've got Al Stohlman's Art of Sewing and have read another book.  It also wasn't addressed in the first workshop I took...  This has also been the reason i think, that I'm spinning with all the glue/cement choices out there.

So what I'm wondering about it, is when two pieces of leather are fastened together, what roll is the glue playing vs the stitching?  In other words, is the glue mainly holding it in place and the stitching is what is really giving the product its structure?  Is it a 50/50 deal?   Is the glue kind of a backup for the stitching?

This has also affected how much glue I'm putting on my watch straps.  This last strap I made, I went close (1/8" or so) but not to the edge of the strap when I glued it (Barge Cement), so that when pressed together I had almost no glue come out the sides.  Will make cleaning up the edges - burnish, or edge paint - a lot easier.  

Thanks in advance for your time,

Neil

[fredk]

On joints of low stress the glue is sufficient. On joints of high stress the glue only acts as location grip, the sewing is the main joiner

Glue, to be very basic, only soaks into the first few layers of leather fibres and under stress the leather joint can pull apart, ripping out those fibres. On the other hand, sewing goes right through the thickness of each leather and pull them tight allowing the joint to with stand more stress.

I make game boards. Sometimes I cover a board in thin leather, then apply a square of thin leather on top of that to be marked out in the gaming squares. This is a low stress joint so I only glue that top piece of leather to the main one. However, the joint of a gusset in the side of a bag is a high stress joint. The joint needs to resist the pull of the front/back panels in a bag stuffed full, so glue (or double sided tape) to hold the gusset in place then it is saddle stitched. The sewn joint in this case is stronger and more reliable for the job. A good strong glued joint helps to re-enforce the sewing but cannot replace it

Another low stress joint, a fold over key-ring, where a piece of shaped leather is folded over on itself, capturing a split-ring for keys. Glue only will do this

Gluing a two or three layer leather joint allows the join line to be cleaned up and burnished. I go right to the edge of my leather with the glue. I trim the edge after sticking together and also maybe sewing. The trimming cuts away any glue ooze. I'm always careful that the ooze is very minimal and has no chance to get on the face of the leather.

With more experience one can gauge just either how close to the edge to go or how wet to have the glue so as it squeezes down it squishes towards the edge. I put contact glue on wet on the inner of the joint spreading it towards the edge so it gets a bare minimum of almost dry-ish glue. When its clamped up very, very little is squeezed out. If a section doesn't glue down the way I like it, or I've left a section un-glued for a reason, I use a thin blade on a modelling tool to apply a thin smear of glue later.

I think in your case, I would take the glue right to the edge. Having allowed a few extra millimetres on the sides, trim the edges to size.

 

hth

edited to correct spelling errors

Edited July 27, 2019 by fredk

[NeilMott]

Fred, 

That was hugely helpful!  Thank you very much!!!

Neil

[Rockoboy]

When using contact cement, I have found if I get any squeeze-out, I can rub with a piece of canvas to remove the glue. I have also successfully cleaned contact cement off a face surface with canvas. Just make sure you get to it before it fully cures.

[Handstitched]

I have found that  using contact glue is like having an extra pair of hands, especially during sewing, hand or machine. Also, I often use cotton buds/tips  or ' Q ' tips instead of a brush  so I can apply the glue precisely where I want it and to avoid any excess. They're  so cheap & disposable .  Brushes are great for large applications, but they do need to be kept in acetone, so the bristles don't go hard  and  they  need to be cleaned every time. 

HS 

[beeb44]

Can I add to this  please..as a total newby i discovered that while trying to saddlestitch soft leather (goat) it unknowingly went out of shape...ie it stretched as I was pulling the edges together as I was sewing....I discovered this only when I had finished!....If I had used glue prior to my stitching I think I would have made a better job..fortunately I'm making a rustic style tobacco pouch and the style will sort of let me get a way with it but of course..I know it's there...so next time if the application is possible I'm going to glue first and then stitch.

[mikesc]

Goat is very stretchy, goats can climb rocks, mountains..even some trees..Goats will try to climb almost anything including cars..don't park near goats.

Edited August 3, 2019 by mikesc

[fredk]

yeah, wot he says.     One time some of our goats got out of their field. I found three of them on top of my Caddy. Not too much damage done tho.

[beeb44]

Yes but not all goats are equal..i think Irish and Breton Goats are not as laid back as Ozzy goats!...but i do need to stick the buggers down under!! Lol

[Halitech]

If you are stitching as well, you don't need to glue. 90% of the things I do are assembled with double sided crafters tape and then either stitched or laced. I prefer the tape in most cases because I can reposition if needed either before I even start stitching, or as I'm going along.

[beeb44]

12 minutes ago, Halitech said:

If you are stitching as well, you don't need to glue. 90% of the things I do are assembled with double sided crafters tape and then either stitched or laced. I prefer the tape in most cases because I can reposition if needed either before I even start stitching, or as I'm going along.

Good idea Halitech..Thanks

[canonitr]

there is a product from columbus that is called rub-rub .. basically its a piece of rubber (raw rubber ?) .. after gluing, u use the rub-rub to, well, rub the squeeze out ... 

i used to have issue with gluing the soles to my shoes because of the squeeze out making it unsightly..