Adhering Sole To Leather

[Leather Bum]

I'm making some sandals and plan to use Birkenstock EVA soles. What is the best way to attach the EVA soles to the veg-tanned footbed? Should they be glued and stitched, or is glue by itself sufficient?

If only gluing, what do you all recommend as the best glue for this application?

Micah

[Leatherimages]

Micah,

I use Duall 88 Contact Cement. I've been getting mine from Seigels (sp) most often, but it's available elsewhere.

Barge still works ok, I believe, we just need to change how we use it.

If you scratch and brush the dust off, just cementing the EVA should be just fine.

Good tight stitches could actually cut the crepe, so I'd advise against that.

I'll recommend two coats, especially with cement as thin as we have now, with these toluene free cements.

Think of the first coat for the underneath cells and fibers, and the second as for the union.

Be deliberate around the edges, that's where dirt and dust get in, and can work the sole loose over time.

If you're real good with a good sharp knife, you might get by without sanding the edge.

But sanding, with good suction for dust, is the best way to get a good edge with crepe.

One last thing about your veg-tanned footbed.

(actually we usually only refer to the topside or insole surface as the footbed)

But it's best if the flesh side is down, so as to provide a more porous surface for the cement.

And again, I'll just emphsize the importance of scratching and dusting it clean before two coats.

Good luck

[Leather Bum]

Thank you so much, Paul, for all this great advice!

One last thing about your veg-tanned footbed.

(actually we usually only refer to the topside or insole surface as the footbed)

But it's best if the flesh side is down, so as to provide a more porous surface for the cement.

And again, I'll just emphsize the importance of scratching and dusting it clean before two coats.

And that relates to my next question. There are three layers of veg-tanned leather cemented together, so at some point the grain sides of two pieces will need to be roughened enough to adhere to the next layer. The way I'm constructing it, two of the pieces will be cemented grain side to grain side. I figure it would have been better to layer them flesh side to grain side, but either way, it seems the surface needs to be roughened enough to produce a good nap and open the tighter grain-side fiber structure to provide that more porous surface for the cement, as you mentioned.

What can I use to scratch up the grain sides so the cement will provide a strong hold? I tried using 60-grit sandpaper and even a coarse wood rasp, but they do not seem to cut deep enough. . .

Thanks again,

Micah

Edited July 23, 2010 by Leather Bum

[Leatherimages]

What can I use to scratch up the grain sides so the cement will provide a strong hold? I tried using 60-grit sandpaper and even a coarse wood rasp, but they do not seem to cut deep enough. . .

Micah,

It's not really necessary to go deep, you just want to open the grain. The primer coat will get in there and do it's job.

I run 24 grit on my sander, and keep a piece of it on my bench to scrape small areas. You don't really need to create such a rough surface as the flesh side is. But the better you can break the grain, especially along the edges, the better your bond will be.

There is a wire surface "sole rougher" available through shoe finders, maybe a local shoe repair shop could help you get one. Or maybe a barbeque grill wire brush would suffice.

In the center area you can be a bit more random with your scratching, just be sure to compress the two layers from the center outward, to avoid air pockets, which can work their way out to the egdes and cause the layers to separate.

I might be able to comment better if I could see what you're working with. And I don't quite see your three layer construction.

Do you have any pictures?

[Leather Bum]

Once again, I missed your reply (maybe the topic subscription feature isn't quite working?). . . Thanks again for the help. I ended up using a brush kind of like this one to really scuff up the grain side before applying the cement.

I'll recommend two coats, especially with cement as thin as we have now, with these toluene free cements.

Think of the first coat for the underneath cells and fibers, and the second as for the union.

Be deliberate around the edges, that's where dirt and dust get in, and can work the sole loose over time.

. . .

The primer coat will get in there and do it's job.

That's great advice, and it makes a whole lot of sense. I remember seeing a post or two on The Crispin Colloquy regarding using several coats of cement. I used DAP Weldwood -- which, as far as I know, isn't listed as a footwear-construction cement -- so I wanted to be sure it would hold well. . . ( I'm crazy, really ) The first coat was heavily thinned with lacquer thinner, the second was not so thin, and the final coat was full strength cement.

Here are a couple pictures that may help illustrate the three-layer construction:

A third and final layer of leather (4-5 oz.) was cemented to the second layer, so the EVA sole would be cemented to the sandal across it's entire surface (in hopes of the best adhesion. . .?) Then all three layers were saddle-stitched together (yeah, it was a little difficult.) Finally, the sole was cemented in place, trimmed, and sanded; and the leather edges were dyed and finished.

I guess I'm pleased with how the sandals look. I wish I could say they work perfectly and are comfortable. . . but they definitely are not. The strap by the toe and the heel piece are quite uncomfortable. The straps are 3/4" wide, 8-9 oz leather with smoothed/finished backs and edges (to some degree anyway), but even after oiling them and wearing for a day, I would have to seriously consider the project. . . unsuccessful.

Anyway, many thanks to Jordan (topic 1, topic 2) and Serendipitydesigns (Roman Sandals) for inspiration, ideas, and material sourcing.

And thank you again, Paul, for all your great advice as well!

Micah

[BIGGUNDOCTOR]

I recently read a "hippie" leatherworking book titled Leather circa 1972 or so. They mention taking great care to avoid ankle, and other foot bones for maximum comfort.

They also angled the holes into the sole to allow a more natural flow of the straps.