All messages posted prior to 25 February 2002 have been moved to the first Crispin Colloquy CD Archive. Those interested in obtaining a copy of this CD need to contact admin@thehcc.org

Admin--06 May 2002

This message is for the Orthopedic shoemakers out there. And it is NOT about correcting a common foot problem - this was just the closest topic.

One of my new students this semester has very unusual feet, and we are looking for an alternative last for her. I think she would like to take a non-traditional approach to making shoes appropriate to her feet, but I would like to get the perspective of a Orthopedist. Could someone please e-mail me off-forum - I will try to describe her anatomy.

Thank you,
Erick

I think that I had better add that this is an extreme deviation from average anatomy, but she is symetrical.

Hope that helps,
Erick

The last needs to follow the foot...

Found an interesting web site explaining the use of Renia cement and primers. Specifically interesting for pedorthist and people that do shoe modifications and repairs. Seems like a Renia commercial but with useful information. www.mcfarlandsshoerepair.com

Rob

Esteemed colleagues,

I've been contacted by a customer who claims to be highly allergic to organic solvents. I'm trying to figure out if I can do the job and price it out. Thank goodness it does not really have to be much of an orthopedic shoe. The way I would go about something like this is gather all materials I would use, leather, fabrics, padding materials,
reinforcement tape, soling and whatever else I can't think off right now. Give the customer a sample off all these materials with instructions to wear them on or close to the skin for about 2 weeks. If any allergic reactions take place find a different material.

With solvents being the problem I would have to find non organic solvent glues. I've read previous posts on water based cement and actually have a can in the shop to try. Anybody have any thought on what to use in stead of rubber cement for my uppers, the folded edges, holding the parts together before stitching etc.

Anybody with suggestions on a different or better approach to test what materials are “safe” to use please speak up. I'm not working on much experience here.

Thanks
Rob

Robert,

An instructor in New York I know has her students use Latex for everything but attaching soles. I would think that this would work unless this customer is allergic to latex (maybe a synthetic latex would work in that case?). A water based adhesive would probably wok for attaching the soles if you are able to suplement with a McKay stitch?

Erick

Robert

I just bought some water based cement called Casco Contact. It is one of the water based we used at Jakobs shop. It takes along time to dry so you will have to have some other projects going at the same time to avoid waiting to much. You could also go back to the old way of making toe boxes. I was tought to use Hersch klæber on the lining and then lay the wet shived leather pc on the toe. Pin, more klæber and start beating with the hammer to harden and shape the box.

You could treat it like a silk shoe. Use H-klæber and sew and sew and sew ........

My coffee and food is waiting
CW

Rob

I thought I would finish what I was thinking of. I learned to peg alot more than most people do. An example could be when pinning the heel. I peg all the way around the heel to give a cleaner featherline, its also a good way to suck up an area like the spots where parts of the upper meet.

If I think a shoe needs extra stiffness, I peg the shank cover(leather not skind). This is more symbolic if you look at the distance between the pegs. All the pegs hold the counter very well!

You could do it simply for the holding effect. If the customer wants a glued welt you could peg it from heel to met. line. This could take the place of pegging the the heel after pinning.

It's time to work on the honey do list.

CW

Robert,

The water-based all purpose I get from Upaco can serve in every application as a solvent based cement...with some caveats:

It's about two-thirds of the way to the same bonding strength as solvent based all-purpose, so while it could be used in lieu of rubber cement (perhaps thinned a bit), you'd need to be pretty sure and pretty deft when turning edges, etc.. That said, I use WBAP whenever I'm assembling a boot made of oil stuffed leathers. In fact, it's nearly the only thing that offers any kind of reliable bond on such leathers.

When cementing on soles...prior to stitching(it's not strong enough for cement sole construction)...it is a good idea to have the sole well mulled. The soling leather needs to conform to the bottom of the boot without significant separation stress for the cement to hold. That said, I've put the whole boot together using WBAP with no significant problems.

Now, another thought...since the solvents in all-purpose and rubber cement are volatiles, they evaporate quite quickly and thoroughly. In the absence of further data, I would question whether your customer is allergic to solvents or to the chrome salts that are prevalent (sometimes in extreme) in most modern leathers. I've seen that in customers of my own. Of course a pure veg shoe assembled with water based all-purpose would surely answer all questions. But as I'm sure you know, some outfits (perhaps unknowingly) will sell retans as pure veg. Only the burn test will proof the leather reliably.

Tight Stitches
DWFII--Member HCC

Robert,

The two week testing of materials and components with the client sounds right. As far as cements, use a few as possible. As you know there are many people allergic to latex. Stitch- when bottoming (and every where possible), to avoid chemical bonds. Leather is always a problem as DW points out.

http://www.basicadhesives.com/

I just received, but did not have a chance to try, a sample kit from the above company. They specialize in waterbase adhesives and edge dye. I've assisted someone who uses their latex for upper assembly and it's great. Basic Adhesive's sample kit is comprehensive with simple directions, for about a dozen of their products.

I still have not done the pedelin elevation we talked about, but will let you know the results soon.

best to all,

David

All,

Thank you so much for the input. As usual one question answered brings on a dozen or so new ones.
I've spoken shortly with this customer on the phone and have not met face to face as of yet. I'm trying to work that out hopefully some time next week.
First of all I obviously have to find out if this organic solvent allergy is just a suspicion of the customer or has been confirmed by her doctor or some other independent source. DW hit on a good point on the evaporation of the solvents I'm just not sure if there would be any residue that does not evaporate so that has to be answered before I would even consider taking on the job. If the allergies are as severe as she makes it sounds I'm sure she's under the treatment of an allergist who may be able to help out.
I'm just realizing that I have to check into cross-contamination just as a food facility that handles nuts needs to list that on the labels of food they produce even if the food has no nuts in it.
Erick,
Do you know where to source the latex glue? I would be surprised if my regular finding place would have it. Any chance you know the brand or could put me in touch with your contact in NY? I have been thinking about having to stitch it. I may inseam but an other option is a McKay type stitch. I would do it by hand and lay the stitch in a groove on the outsole. That reminds me I have a picture to post and would like to know what that type of awl is called and if it's available in the US. I'll do that over the weekend.
Chris,
I forgot all about Hirsch Kleber. I have worked with that and it's much nicer to work with than press cement. I don't really have any experience with pegging. Do you do this on the heavier shoes like men's work boots or on most - all shoes? My grandfather had a manual peg machine in his shop. I believe my Uncle has it. I remember as a kid barely able to reach the paddle making pegs. Even than it didn't take much to make me happy.
I don't quite understand what you mean by What is the average distance between you pegs?
DW,
The water based all purpose, the one I have in the shop is DAP from the regular hardware store, do you have experience that the Upaco is better? When sewing through the all purpose does it gum up like regular all purpose does? I could just not fold any of my edges, that would cut down on a lot of glue work.
I'm certainly aware that allergies to the chrome salts in leather are well known. That's why I would gather all my materials, take a sample to give to the customer (I have even heard of allergists gluing the samples to a customers back) and put the materials aside so once it checks out the same skin is used as was tested. A different skin that seems to come from the same batch may have been treaded slightly different so one has to be very careful about that. You mention the burn test, in your experience does it always detect any chrome salts or do you think there is a (small) threshold that needs to be met before it shows.
David,
Good tip on the adhesive company, please let me know how that works out for you. In the sample kit for leather adhesives I don't see the latex listed. Is it included or is that a separate sample?

What are the advantages or downsides to using latex cement v/s rubber cement? I have not used latex so I'm curious if it's something I should try regardless of this project. Any thought are appreciated.

Rob

Robert,

I don't have any experience with DAP. I have used several different types of "synthetic latex"/WBAP. The Upaco is the best I've seen. It produces a strong bond and responds much like SBAP. It can even be heat reactivated. More, it bonds to solvent-based all purpose like they were brothers.

I don't have much problem with solvent based all purpose gumming up the needles while stitching (although I know it can happen) and I have never had it happen with the Upaco. Maybe it's the fact that I let it cure overnight be fore attempting to stitch that makes the difference, I don't know. The big advantage of WBAP (AKA synthetic latex) is that it will adhere to oil stuffed leathers. When solvent based cements are applied to this type of leather, the solvents immediately loosen and absorb the oil and you end up with a gummy slurry rather than a cement.

Re: the burn test...I think it will always produce a unambiguous result if you burn enough leather--maybe a ½" x ½" piece. I've done "blind" burn tests on chrome, veg, and various retans...never had it fail me.

Tight Stitches
DWFII--Member HCC

DW,

patience is a virtue, I usually glue and stitch within minutes. I will try contact cement and let it dry over night. See how my machine will handle that. Thanks for the tip.

Rob

Rob

I ussually use 3.5*16 when I use them as mentioned because we have used cement først and then use the pegs to even out the feather line. If you are not sure of the strength of the water based cement regarding pinning and soling then pegs would help to hold.

When I peg around the feather line after pinning, they are ca every 8 mm. When I use pegs on the shank cover (leather not skin) it's ca 1.5 -2 cm. If you are going to peg the sole on you could go directly to larger pegs and peg the insole,upper, shank cover and sole all at once with two rows ca. .5 -.8 cm between them. After the met line a single row to avoid the shoe-boot being to stiff.

I am going to play with an idea soon; Wood glue for boat building. People put different things in the holes before pegging. I am sure that the wood glue for boats is going to hold the pegs for ever.

About the klæber, I don't know any body here in dk that makes toe boxes with press cement and leather. It's the orth. materials or the leather and klæber combination.

If you sew a mid sole on with a flat awl you could hide the stitches all the way against the upper.

By the way we peg the old fashion way with an awl and hammer.

I'll stop here It's been a long day

CW

Rob, plaster question. I just poured plaster into the foam impression foot molds. What kind of plaster do you use for this? I used dental lab plaster because it has no shrinkage, but it sets so quickly that I didn't get a smooth top surface--sort of had to spread it with a knife like cake frosting. Won't know till I unmold them if the bottom surface came out OK. But I didn't get a perfectly level top surface because it thickened so quickly.

Jenny

Jenny

I use regular plaster of Paris. I like the DAP but my local Lowes seems to have discontinued it so I get whatever brand I get my hands on. The DAP plaster seems a little smoother than most other ones. I don't get to much shrinkage as long as I make sure to add enough plaster to the water, leaving it to thin will make it shrink. I make it a little thicker than the consistency of syrup. Once the mold if filled and before the plaster sets I tap the mold so the service smooths itself out. Trying to smooth it with a utensil only makes things worse I find.
I also have a 4x4, about a foot long in the shop. Sandpaper tacked to one side and I can move the mold back and forth to smooth the back after it has set up and is out of the foam.

I never worked with dental plaster but I find shrinkage to be minimal. You are always working with a margin of error, the foam box will settle in some just by the weight of the plaster in it. Not a big deal since once you modify the mold you really no longer work on a foot, it's an abstract mold that only has a number of benchmarks based on the actual foot.

Rob

Rob, not quite done with my foot impressions...I'm building out the toe area right now. Dug out some old orthotics I never wore. They look like they're made of plastazote, perhaps p-cell or microcell puff, with a layer of cork filling in a few areas on the bottom (back of the heel, outer and inner arches).

When I put them on the foot impressions I am making, the arch of the orthotics is less pronounced, yet when I put the orthotics in my shoes, the arch fills my arch completely...more than if I put the orthotics on the floor and stand on them. It is obvious this is because of the contour of the insole of the shoe. Is there any easy way (although I am finding NOTHING is easy )to adjust the bottom of the orthotic to the shoe so it isn't distorted when you put it in the shoe?

Also, is it a good idea to put some soft material like pink plastazote in the outer and inner arches so it can compress if the support is too high? The arch area on my impressions is about 7/8 inch high at the highest. Thanks!

Jenny

Jenny,

Any particular reason you did not wear those orthotics? Maybe because they didn't fit right. Don't go to much on those old orthotics unless you know they are (still) accurate to your feet.
The key is really how well the foot impression is taken, it’s not hard to take a foot impression in the foam box as you did and make the arch to high or to low. I Think I explained how I hold the ankle with my thumb and index finger use the outside carpel area of your hand to press down the center of the foot.
A common mistake it to first press down the heel and then the forefoot or vise versa. This will create an arch both medial and lateral that is too high. Once the mold Is made a way to check this is looking at the mold, if it looks like this (this view is looking at a foam mold from the outside of the foot) it should be fairly flat, not arched like this on the outside. If your mold is like the image you may still be able to use them but need to grind the bottom of the orthotic in a similar hollowed out shape. It can be done but it really is not the preferred way. This second screen shot is a much better mold. (apologies for the quality of the images, had to get them together in a hurry today)

I would not work too much with soft materials like Pink PZ or P-cell (nearly the same thing, different manufacturers) It would compress to fast and not give you anything structural for any support. You would have to remake them quite regularly. If you start out with to much material and compress it you will be uncomfortable for some time till it “settles in”
To start I would take a piece of cloud EVA 1/4th” and mold if over you cast. Add another layer, same thickness but now only go from in between the toes and the ball of the foot to the back of the heel. If you have a different color it makes it easier once you are grinding. Grind the bottom flat so that you go through the second layer and half way through the first. The arch will not be totally filled but leave that as it is. Now try them in the shoes. If the arch is to high because of the way the mold was you will feel it but since the insert can collapse some it probably will not really hurt your foot. You can now slowly fill in the arch area as you feel is appropriate. My experience is that rarely you need more than 1/2” material in the arch, at least in a mass produced shoe, this is due to the way the arch in the last is “undercut”. Also realize this is not an absolute measurement, it's all proportional so the size of the foot is a factor. The “easiest” way to get the inside of the shoe is to take a copy of the insole. If you make the shoe this is easy, any other way, take a piece of paper and try to trace the insole. Once you make the orthotic to that outline your nearly done. Sounds easy doesn't it

Adding to the toe area, it is much easier to do this before you pour the plaster in the mold, take a cardboard outline of the insole for the shoe it needs to go in, line it up in top of the foam box and with a sharp knife, cut along the front and take out the foam in the toe area. (you can also just press it down)

Let me know if you have any further questions.

Rob

Thanks so much, Rob! I did it exactly wrong as you described ! Heel down first, then forefoot. Oops. Glad I found out before I spent more time finishing them.

Do I understand you correctly that when building the orthotics the second layer of material goes past the beginning of the ball of the foot to perhaps where the toes join the foot? I had expected to stop just before the ball of the foot with the second layer. Is this to get a smoother transition? Isn't it hard to sand evenly halfway through the first layer to get a consistent thickness under the forefoot?

I have to say, I am learning so much by doing things wrong ...not just with this, but with my lasts, too. It is just amazing to me, and a real adventure!

Jenny

re not wearing my orthotics...The curve in at the top of shoes' heel counters that ordinarily hurts the back of my heels, hits in even a worse place when the heel is raised by the orthotic. Also, the orthotics always seem to fit quite differently once they're in the shoes.

So, my solution is to make my own shoes that don't hurt the back of my heels and have room for the orthotics, and make my own orthotics, too. And thus, here I am!

I may post a picture later of my old orthotics. I think the softer pair are pretty poorly made. I think the hard ones are too hard for my feet. Plus they go only to the ball of the foot, slip around in my shoes, and have a rather large and abrupt metatarsal pad.

I am hoping by making my own that I can't do worse, and I might do better, eventually.

Jenny

Jenny,

Placing the second layer of EVA, I like to bring it beyond the ball of the foot but do grind most if not all off this off. You can definitely keep it behind the ball, just be careful to go far enough so you don't end up with a gap if your a little short. The consistency on the thickness you get by keeping a close eye on the angle you hold the orthotic and mold when you grind. If you pour the mold on a very flat service and tap the box to even out the top the flat top of the mold becomes your reference plane. Just check regularly not to grind off to much.

So after learning all this the hard way is there a book in the future? Almost seems like a natural next step. Should you make a more like a comedy or a work of fiction?


That's the spirit. Necessity is the father of all inventions after all. Just remember me when your rich and famous.

Rob who? Never heard that name

Rob, I think it will be a comedy/tragedy!

Do you use a flat belt sander to sand the bottom of the orthotics? I was planning to use a sanding drum, similar set-up to the Sani-grinder. Using a curved drum, it seems like it would be hard to get the ball of the foot area a consistent thickness. Please elaborate!

Here are pictures of my old orthotics:

The rigid ones:



The softer ones:



Love to hear your opinions of them, and anyone else's, too!

Jenny

Jenny,

Looking forward to that book, Do you take advanced orders for a copy signed by the author?

On the grinding I use a Sani-grinder a drum sander or the Jackmaster, a belt sander. I'll get a couple of pictures together on what I mean getting the reference from the top. It'll take me a couple of days though.

On the orthotics, the hard ones do have severe metatarsal pads, in itself not a bad thing but these orthotics being 3/4 length have a tendency to pulling you foot forward, the very smooth pleather topcover and large metatarsal pad make it worse. The advantage of this type of orthotic is that it will keep it's shape independent of the shoe you wear it in.
The second set looks like a tri-lam base, EVA, poron, EVA. With some cork in the arch area. Hard to see how thick the heel is but it seems like most of the tri-lam is still there. Looks like the mold they were made on had a lot of the arching I talked about earlier and based on your Harris mat imprints (as far as I can remember, I will have to get them from the shop to confirm) your foot is not like that.
The bottom of the orthotic is also not really adapted to a shoe. If you look at the shape of the average insole it cuts in a lot more under the medial arch. If you want a consistent fit you match an insole shape. This does not mean you can wear those orthotics only in one pair of shoes, it does limit the shoe selection somewhat. The plastazote is just a cushioning layer, does not do anything structurally.
Just my .

Rob

Rob, you are exactly right! If I put the second pair of orthotics on on the floor and stand on them, they don't quite contact my arches. When I put them in shoes, the arches are too high. Thanks for enlightening me as to the reason, I hadn't put 2 and 2 together on that!

Also right about the first pair. My feet would slip and slide on them, and they would slip and slide in the shoes, even when I tried to secure them with double stick carpet tape. Probably should have tried securing them to my FEET with the carpet tape ! The metarsal pads were also a little too much.

Jenny