Moulding lined leather

[Huw]

Hi,

I'm working on a project which needs lined leather (I'm using pigskin for the lining)  and requires a little moulding. Not full wet moulding - but wetting the leather so that it retains a bend.

Do I line the leather first or do I have to do the wetting and moulding before lining? All the tutorials I've read mould the leather first - but they're usually making unlined bags so I'm not sure if the tutorials are relevant.

If I line first (this is what I suspect is the right way to go) do I need special adhesive? I have a PVA type leather adhesive from Tandy or Evo Stik Timebond in my workshop - any recommendations?

All wisdom welcomed - I could use trial and error but it seems like a terrible waste of good leather.

Cheers

Huw

[Huw]

Nobody? :-(

[JLSleather]

It's going to depend on what you're calling "molding",and where the shaping would be.  And when I hear molding, I assume we're talking about vegetable tanned leather (just to be clear).

So, if I'm shaping an object and relying on it to hold it's shape without wet forming, then I'd line it after forming.  Examples include a handbag, where I want a flap to remain closed when teh clasp is opened. I would glue the layers "on a curve", so that it naturally wants to return to that closed position.  Or a gusset on a case -- I form turns and corners before lining them.. since I don't want 'puckers' and 'boogers' in the corners, especially if there are zippers involved.  In this case, I likely don't even wet the leather to form the bend.

On the other hand, if I'm wet forming, I assume it's likely because 1) it's a fairly complex shape which all layers have to fit, or 2) it's a spot where I'm not going to be able to put in a lining once it's formed.

[Huw]

Thanks for the response JLS. Yes I'm using veg tanned leather, and the final shape I'm after will resemble a U shape.

Can you say a little more about how you glue layers 'on a curve'?

Maybe an alternative plan would be to glue the lining at the same time as the forming. The glue would take longer to cure but I guess that might work ...

Thanks for your input. Much appreciated.

 

[Dwight]

It would magnificently help if in fact we knew what you were doing.  Dual leather for a curve that has a radius of 20mm (about 3/4 inch) is one thing, . . . a curve that has a radius of 200mm (almost 8 inches) is a totally different subject.

Personally, . . . I have made it pretty much a standard that I do as much as I can by gluing first, . . . forming later.  Most of my "work" is holsters, belts, and knife sheaths:  meaning any forming is close radius type work and I virtually never have any problems. 

I do not use glue, however, . . . never really got the hang of that sticky stuff, . . . prefer solvent based contact cement, . . . when it goes together, . . . the leather rips if it comes apart.  The mfg I use is Weldwood.

May God bless,

Dwight

[TinkerTailor]

The real issue is that with any bend the material on the inside of the curve bunches up and wrinkles because it needs to be shorter as the radius of the bend gets tighter. The extra material has no where to go. Of course the degree of this bunching depends on the thickness of both leathers and the degree of the curve. The methond JLS states is a good method especially for thicker leathers. I use this method on all my bag flaps. For strapping, and smaller projects, If the lining is thin enough and the main piece is heavier, you can sometimes stretch a piece of lining a little larger than the project and tack it to the table, then glue it on. This works good for belts and straps. Tack one end, stretch the liner lengthwise, tack the other and then glue the strap on top. You can tack down and stretch a whole lining hide and lay out the strap pieces on it all ganged up. Cut the lining and separate the pieces after the glue dries. I find in many cases this is easier than gluing the item on the curve.The idea with both methods is to have the lining lay flat on the curve and stretch some when you straighten it instead of having too much material inside the curve when its folded.

As to the adhesive, if you are stitching,and just holding the pieces until you get it stitched, any leather glue will work. If you are relying on glue alone, or in large areas strong glues are needed to prevent liner separation during use.  I personally use heavy duty contact cement because it is stuck hard instantly and allows me to move on without waiting for the glue to dry. It also does not let go with use. Downside is, you gotta aim right cause once the pieces are stuck, there is no repositioning. In the states i think they like weldwood blue contact cement. Up here in Canuckistan, we use LePage.

Edited December 2, 2016 by TinkerTailor

[TinkerTailor]

1 hour ago, Huw said:

Thanks for the response JLS. Yes I'm using veg tanned leather, and the final shape I'm after will resemble a U shape.

Can you say a little more about how you glue layers 'on a curve'?

Maybe an alternative plan would be to glue the lining at the same time as the forming. The glue would take longer to cure but I guess that might work ...

Thanks for your input. Much appreciated.

 

Do some tests with the glue you have and wet leather. Many glues, even water based ones, require a dry surface for best bond strength.

 

[JLSleather]

The "bunching' brings up a good point.  I've tried a bazillion ways to make belts.  I've done them straight and curved.  I've done them smooth and tooled.  I've done them single layer and laminated.  I've done them flat, I've done them in a hat

Take that 2-layer belt for example.  

Glue it flat on a table.  When you wrap it around the waist, the inside layer "bunches" to some extent (and while less obvious, the outer layer stretches).  This causes visible issues on the inside of the belt.  Which, as long as they aren't extreme, aren't a big issue.  

Now, make the same belt, but glue it on a curve similar to the curve of someone's waist.  Since the pieces were glued on this curve, there's no visible marring.  Not to be confused, though --- the inside is still compressing and the outside is still tensing, they just aren't as obvious because the (2) outer bends are allowed to stretch more to "come around" rather than compressing the inner surface.

Either will work. The "problem" then, is that the pieces will try to return to the position they were joined.  

On the belt which was glued flat, it will attempt to return to flat (much like a flat steel spring tries to go back to flat when bent, and why you can "snap" a comb) which does little damage to anything.  This "spring" will relax over time.

On the belt formed on a curve, it will try to return to that curve.  So when wrapped around the waist, the inside layer which was already compressed someone suffers little effect.  But when straightened (trust me, the nicer the belt looks, the more people will want to hold it out flat to "look at it") you are now stretching the inside surface beyond where it started, and you are compressing fibers which were already stretched, very possibly creating wrinkles/cracks in the OUTER layer, or at least in teh finish applied to the outer layer, which is going to be visible from now on.

Point is, it matters both what you are making and the way you are making it...

 

 

[TinkerTailor]

24 minutes ago, JLSleather said:

Point is, it matters both what you are making and the way you are making it...

That is kinda what i was getting at with the stretch trick working sometimes. If you are lining 8 oz straps with 1-2 oz leather, stretching the liner slightly and gluing it flat is basically the same as gluing it on the curve, you are just shortening the inside piece slightly in different ways.  With these thicknesses it should work out beautiful. because the stretchy leather is doing its thing, while not able to effect the main piece due to the thickness difference. Now If it is a 5 oz strap with a 5oz liner, the stretch trick will not work because the liner is too thick in comparison to the outside. This situation is best glued on the curve.  The outside wrinkles and cracks you suggest could very well appear here. It only works when the liner is significantly lighter than the main material. One upside is it can be harder to get floppy stretchy liners on straight, and tacking them down really helps this.