Correcting common foot problems

Post Reply
Message
Author
relferink

Re: Correcting common foot problems

#201 Post by relferink »

Geri,
Most of the O& P guys around here also use fiberglass over stockinette. I'm not a fan of it. In fact I prefer the smooth finish the plastic gives, even with a few wrinkles. The plastic is less than 1/64th” thick so it's really not a unevenness that would concern me. The material shrinks more than that when it cures.
Once you have poured the last and taken off the fiberglass sock hang on to it. Worse case scenario you can close it back up and pour another last from it.
You may not need it but it has saved me a few times when things didn't work out as planned.

Georgine, I'm sure there will be plenty of volunteers to cast your leg. If I make it to Guthrie I'll be one of them. STS sells a long, toe less sock. It's marketed for custom knee braces. If your finder does not have it give STS a call. They sell them directly but if memory serves only by the dozen. They should be able to direct you to someone that sells them individual. If you can't get them, 4” or 6” bandages work just as well.

Jask,
Welcome to the Colloquy. Sounds like you have some first hand experience working with fiberglass. It's nasty stuff, yet gives great results. Are you coming at this from an O&P background or as a shoemaker? Feel free to introduce yourself in the Registry. Looking forward to hear what it is you do.

Fred,
During my apprenticeship we always took a separate bottom profile of the foot and used that in last making, both on wooden lasts and poured urethane.

We are heaving heavy thunder storms rolling in. I'm shutting things down for the night but will continue tomorrow where I'm leaving off now.

Rob
relferink

Re: Correcting common foot problems

#202 Post by relferink »

Fred,
Continuing where I left off last night, we would cast the customer's foot with plaster bandages, this was pre-fiberglass but also take a bottom imprint in a clay basin, later changing over to foam boxes. Then we created a plaster positive and form a clear plastic negative with a Vacu-therm machine. The clear negative can be held against the last and you can see through the plastic what areas need to be build up or taken down. Worked well. In extreme cases we would take a Bondo like product, fill up the negative and press it against the last for a near perfect fit.

From your description it's not clear to me if you slipper casted the foot and casted right over that or made two separate casts. Either way will work.
The best method in my book is till the vacuum cushions sold by Minke. You can't work on them with fiberglass, plaster only but it allows you to modify the customers footprint and than harden it up so you can actually take a corrected, weight bearing cast.

Rob
fred_coencped
3
3
Posts: 120
Joined: Thu Oct 18, 2007 6:32 am
Full Name: Fred Coen;Foot Comfort Center
Location: Santa Fe, New Mexico, USA
Contact:

Re: Correcting common foot problems

#203 Post by fred_coencped »

Rob,
The Vacu-therm machine sounds like blister forming where the clear film is held in a frame similar to forming a BK socket in O&P.It is used also for 5mm poly pro in podiatry at Pro Lab in Calif.
Anyway after making the slipper cast to distal met heads non weight bearing I made the second step a bi valve cast right over the slipper cast and the 3rd application of plaster over the dorsal aspect of the foot with vaseline release agent to seperate as usual.
I am curious about those vacuum cushions by Minke especially in taking a corrected weight bearing cast. Could you elaborate on that point please?

Georgene,
Sorry about Georgette,my mistake,also I didn`t realize your request for above the knee cast and Robs pointing out an sts open ended tubular sock solution sounds very good.A leg cast of that magnitude seems pretty formidable in size and weight.I wonder if you are considering that expandable urethane foam that blows up to about 3 times its size and is as hard as wood gets very hot and exerts probably about 20 psi on the negative mold that requires enough reinforcement for resisting blowing out the mold.

Fred
relferink

Re: Correcting common foot problems

#204 Post by relferink »

Fred,

The Vacu-therm is indeed just like blister forming. Minke sells them as do others, see page 2 & 3 in the Minke machine & tool catalog
Also makes great clear fitting shoes and Nora hypoallergenic healing shoes.

The vacuum pillows from Minke are called the Primat 1500, on page 7 of the above PDF. It's a bag filled with a fine grained sand and the way it works is by placing you customers foot on the pillow, non weight bearing, position it the way you like it and suck the air out of the bag with a vacuum pump. In a stage where the sand is firm but not hard your customer can stand up without deforming the pillow. In this stage you can mold corrections into the pillow. Suck out the rest of the air and it will be rock hard. Take the foot out of the pillow, apply plaster bandages to the foot and when you place the foot back you have the customer stand.
When hard you have a corrected weight bearing cast. The only problem is that fiberglass will sick to the pillow but plaster bandages give a better definition anyway.
It also works great for orthotic castings. In that case you just get the foot corrected in the pillow and fill it with plaster. When hardened you have a positive of the corrected foot that needs very little further work.

Rob

(Message edited by relferink on July 24, 2008)
jask
2
2
Posts: 60
Joined: Tue Apr 15, 2008 11:30 pm
Full Name: jask

Re: Correcting common foot problems

#205 Post by jask »

Geraldine, I usually "powder" the inside of casts with Talcum ( about 1 Tbsp per side) shake it around to coat the whole inside and make sure you dump out any excess with a couple good raps to dislodge any clumps.Powdering makes removal from the plaster positive MUCH easier, more so with synthetic casting material as its weave tends to lock onto the plaster.
I would not bother with dental plaster myself, call a few wholesale building supply yards and see if they sell #1 casting plaster, a 50Lb bag should be about half the cost of a small box of dental plaster. A good rule of thumb for plaster is to mix equal parts by weight, this ensures your plaster is not too fragile.

Rob (and everyone else!)
I have been lurking here for a while, I work as an O&P Tech. and although I have experience with Orthopaedic footwear mods,I have just started trying my hand at custom footwear.I really have been enjoying this forum and the impressive experience and Knowledge (and enthusiasm!!) everyone brings to this group.
gshoes
5
5
Posts: 205
Joined: Thu Feb 14, 2008 10:41 am
Full Name: Geraldine Rabey
Location: Elgin, IL, United States

Re: Correcting common foot problems

#206 Post by gshoes »

Jask,

Thanks for your suggestion of the plain old plaster. I see that you are a O & P person. And I am just a cashier. And I just think that O & P means Orthotics and Prostetics and even that is likely wrong. I am just wondering if plaster may not stand up as well if you are beating on it and nailing into it as much as you do in the actual construction of the shoe. Please don't be insulted that I ask. I just don't want to find out after I have casted it in plaster that it works fine for insoles but not too great for the whole project.

I would like to save the money where and when I can.

Geri
jask
2
2
Posts: 60
Joined: Tue Apr 15, 2008 11:30 pm
Full Name: jask

Re: Correcting common foot problems

#207 Post by jask »

That is correct, Orthotics and Prosthetics.I know a gal who has worked for Safeway as a cashier for over 20 years, and have a great respect for any one that can remember all those codes, move up to 50,000 Lbs with one arm during a shift, and still be able to smile at even the grumpiest customers.

Properly mixed plaster is very strong and able to take and hold a nail, old casts will become extremely tough,(these can be recast if needed)but for a single pair you should be fine. My only concern is that you might break the last while removing the finished shoe. All of the lasts I have worked with "in house" are plaster, however the custom footwear people we use prefer a built up stock last or a last poured with high density rigid foam. Foam lasts are very tough and easily modified or repaired.The foam is the better choice on a final last that will be used again- however this being a first last I would not expect a definitive long term last as your goal. Remember that the foot is continuously changing and what fits well now will certainly need adjustment in a few years.In the case of custom orthotics I will not usually work off of a cast that is more than 2 years old.
I do not know how well equipt your shop is, but if you do decide to work with plaster and have a bench vise I would recommend using a length of3/4" water pipe as a cast mandrel. The pipe can be placed into the plaster while you fill the cast, (viewed from the side it would be slid into and forward as much as the cast allows,with the pipe extending backwards at a slope) and then pulled back about 3/4" so that it is not at the surface of the plaster last when you strip the cast.
this will allow you to secure the last in a vice and free up your hands.
gshoes
5
5
Posts: 205
Joined: Thu Feb 14, 2008 10:41 am
Full Name: Geraldine Rabey
Location: Elgin, IL, United States

Re: Correcting common foot problems

#208 Post by gshoes »

Jask,

I was completely forgetting the fact that these particular lasts will be only used for one pair of shoes. My 13 year old son is 6' tall wearing a size 13 shoe. He is still growing.My objective with these particalar last is to gain the knowledge and skill for future lasts.

My shop is very well equipped and what I do not have, I will get.

I will get the plaster and cast these this week. I look forward to making mistakes that I can learn from. I will post pics.

Thanks again, Geri
paul
8
8
Posts: 1038
Joined: Tue Mar 08, 2005 10:00 am
Full Name: Paul Krause
Location: Prescott, Arizona, USA
Been Liked: 14 times
Contact:

Re: Correcting common foot problems

#209 Post by paul »

Dear fellows,
(Especialy you O&P guys who make vanity shoes.)

Here's my deal. This customer, and the one soon after her, both have severe bunions. Besides a 1" heel and soft leather choices, here is what I've been thinking to do for them for about a year now.
7837.jpg
7838.jpg


What I have done here on her fitters model is pretty obvious, and not original. I've just never done it myself. I think the material is poron. And I've cut it as a cookie to support the negative space created by the "extrusion" of her bunion. I would install this on the liner before lasting the upper over.

And here is what I'm hoping to achieve.
7839.jpg


I'm interested in feed back of all kinds, if you would be so kind.
Both of these ladies are so purty I blush, even though they're in their 70's. And I really would like to serve the vanities of their youth, as much as possible, rather than deliver lumpy boots to them.

TIA for your feedback,
Paul
You do not have the required permissions to view the files attached to this post.
artzend
7
7
Posts: 519
Joined: Sat Feb 10, 2007 10:00 am
Full Name: Tim Skyrme
Location: Agnes Water, Queensland, Australia
Been Liked: 2 times
Contact:

Re: Correcting common foot problems

#210 Post by artzend »

Paul

That looks fine to me, as long as the bunion build up is in the relevant place on the last, what you have there should do the trick. You can't hide the bunions away completely. Never put a seam over the top of a bunion, and maybe a bit of cunning design or use of different leathers can make them much less obvious.

If you run a strip of contrasting material down the centre of the front, that draws the eye away from the outside edges.

Tim
donrwalker
2
2
Posts: 72
Joined: Thu Jul 10, 2008 1:48 pm
Full Name: Donald Ross Walker
Location: Spring City, UT, USA
Contact:

Re: Correcting common foot problems

#211 Post by donrwalker »

Paul

I like the idea. A lot of what our customers are paying for is looks. Fit is always most important but if you can also satisfy the vanity you are playing under par.

Hit em long and staight.

DRWalkerII
paul
8
8
Posts: 1038
Joined: Tue Mar 08, 2005 10:00 am
Full Name: Paul Krause
Location: Prescott, Arizona, USA
Been Liked: 14 times
Contact:

Re: Correcting common foot problems

#212 Post by paul »

Tim,

Thank you for the validation and the cautions.
That's a good point about drawing the eye away. I'll consider how to use it in the future.

Don,
Thank you for your comments as well.
And tho I don't play, I completely agree with your golfing analogy.

It'll be awhile before she can come to try on the fitters, but I'll post pictures when these are done.

Paul
relferink

Re: Correcting common foot problems

#213 Post by relferink »

Hi Paul,

It's not uncommon for us "orthopedic guys" to work in between the lining and upper. Sometime so extreme that I last the lining, add all my buildups and than make an envelope upper that slides over the lining with buildups. Works very well for customers that need ankle reinforcement build into a boot.

Do be careful when using Poron or similar materials that have a memory and will not permanently form to the last. In stead use something that is thermo moldable such as a light weight EVA. If you use Poron make sure you lay it against the lining, careful not to stretch it around the bunion or it will end up pulling back after you pull the last leaving a nasty wrinkle.
For what it's worth, the material in the picture does not look like Poron to me, more like a Zote foam.

It probably goes without saying but these types of lasts may cause mild to severe distress when trying to pull them.Image Do make a fitter to try it and I find that 2 part lasts are easier to get out than hinged lasts.

Just my Image

Rob
paul
8
8
Posts: 1038
Joined: Tue Mar 08, 2005 10:00 am
Full Name: Paul Krause
Location: Prescott, Arizona, USA
Been Liked: 14 times
Contact:

Re: Correcting common foot problems

#214 Post by paul »

Wow Rob,

Good stuff in that one. Thank you. I'll be interested to hear more about the envelope upper technique, maybe at "Guthrie". But it sounds like more than necessary for this one. I do appreciate you confiming my suspicions about doing build ups between the liner and upper leathers.

I remember the fellow who gave me this collection of stuff refering to plasizote in the pile. So you're probably right. It's all pretty unfamiliar to me and there are so many different products like this, so I get confused. Sounds like a thin EVA might be the way to go. By thermo moldable do you mean I should heat it to lay it over and then shape it?

This last came out of the fitter pretty easily yesterday, but the next pair will probably be a real pain. I've already ordered a hinged last for her from Bill, and it's probably too late to change it. But I'll remember that about two piece lasts for applications like this one.

Thanks alot for you advise and suggestions.

Regards,
Paul
gshoes
5
5
Posts: 205
Joined: Thu Feb 14, 2008 10:41 am
Full Name: Geraldine Rabey
Location: Elgin, IL, United States

Re: Correcting common foot problems

#215 Post by gshoes »

Hello All,

I am again off schedule and I could use some help?

I am about to duct tape up my STS and cast them in plaster using equal parts by weight of water and plaster. I am having great difficulty getting all of the cloth stocking out of my STS cast. I am considering trying to light the leftover fabric on fire to singe off the remaining cloth. But common sense tells me not to. Is it imparitive that all of the remaining cloth comes out or can I cast this in plaster without all of it out?

Jask, You suggested that I use talcom inside the cast to assist in the unmolding. Can I use cornstarch?
Geri
headelf
3
3
Posts: 138
Joined: Wed Dec 30, 1998 7:01 pm
Full Name: Georgene
Been Liked: 1 time

Re: Correcting common foot problems

#216 Post by headelf »

Yikes, cornstarch will act as a glue when it gets wet. Bookbinders use cornstarch to make paste. You may never get the casting out. Just my two cents.
Georgene
gshoes
5
5
Posts: 205
Joined: Thu Feb 14, 2008 10:41 am
Full Name: Geraldine Rabey
Location: Elgin, IL, United States

Re: Correcting common foot problems

#217 Post by gshoes »

Georgene,

Thanks. I will get the Talcom today. Haste makes waste.

I would not use this stocking in future castings. It is extremely hard to remove all of it.
Geri
relferink

Re: Correcting common foot problems

#218 Post by relferink »

Geri,

I always have a layer of plastic between my fiberglass and the stockinette so this is not one I've had to worry about. If memory serves the O&P guys have no problem pouring plaster with the stockinette in the mold. (with talcum powder) Do not burn it off, I think that the urethane impregnated in the socks is flammable. Be careful of loose pieces of stockinette. If it has partially come loose you may want to trim the loose pieces off. Smoothing the mold will be a little more work. Do not pour the plaster in a plastic bag inside the mold, that does not work.

Rob
jask
2
2
Posts: 60
Joined: Tue Apr 15, 2008 11:30 pm
Full Name: jask

Re: Correcting common foot problems

#219 Post by jask »

Hi Geri
Sorry I missed this- I was out of town.
I would not recommend trying to remove a cotton sock or stockinette from a casting sock,the urethane resin is a resin glue and you risk distorting or damaging the cast.Powder the inside of the cast/sock heavily with Talc, knock loose any excess and fill with plaster and mandrel pipe. if you have not filled it yet trim off any loose bits or flaps of fabric as close to the cast as you can- fill ,strip off the casting sock and "touch up" any voids that pull off with cotton tags.
gshoes
5
5
Posts: 205
Joined: Thu Feb 14, 2008 10:41 am
Full Name: Geraldine Rabey
Location: Elgin, IL, United States

Re: Correcting common foot problems

#220 Post by gshoes »

Jask,
I casted the plaster molds today. It turned out great with the talc. Next time I don't think that I will worry about removing the sock at all. I did leave quite a bit in this time and it did not seem to be a problem. I do not think that I could ever use the same STS molds again. There was a great deal of distortion caused when removing the plaster. I employed my son to mix the plaster and hopefully trigger some interest and knowledge from this whole process.
7902.jpg
7903.jpg
7904.jpg
7905.jpg
7906.jpg

Geri
You do not have the required permissions to view the files attached to this post.
jask
2
2
Posts: 60
Joined: Tue Apr 15, 2008 11:30 pm
Full Name: jask

Re: Correcting common foot problems

#221 Post by jask »

good job Geri! the casting socks are not intended to be used to create more than a single cast. The plaster cast is easily modified while the plaster is "green" and moist, as it ages and cures it will be a great deal more work to modify.The standard tool I usually reach for is a half round Surform file (cheese grater or autobody file)and a small section of sandscreen sanding cloth, both of these should be easy to find at WalMart or an automotive supply shop. You will want to use the surform to scrape off any casting artifacts ( sock wrinkle ridges,cut strip artifact,etc) followed by a scrub down with the sandscreen- keep a bucket of water handy while doing this, use the water to wet the cast and sandscreen as you scour the surface to reduce the fabric pattern. The goal is not to remove all of the detail,if you remove that much material you will reduce the volume of the cast to less than it should be. It is very important to not remove excess material from the bony landmarks of the foot,- the ankles,rear of the heel,navicular(above the instep) shaft of the 5th ,and the outsides of the metatarsal heads.

To produce a proper last that will withstand some abuse from nailing you will need to add your toe buildup and finalize this cast, and then recast to create another that is poured up as a single one piece pour. you could risk lasting on this but I think your toe extension would break loose the first time you drive a few nails in that area.

As for the toe build up.. ensure that all the talc is cleared off the "toes" of the cast and scratch up the contact areas to give the new plaster something to lock onto. I also like to drill a few holes to slide a couple of 2" nails into the cast as this helps hold the build-up.
gshoes
5
5
Posts: 205
Joined: Thu Feb 14, 2008 10:41 am
Full Name: Geraldine Rabey
Location: Elgin, IL, United States

Re: Correcting common foot problems

#222 Post by gshoes »

Jask,
Ok. You just filled in a huge piece of my puzzle. I was unsure of how to turn a foot shape into a last shape and then actually use it to make a shoe on. The second negative cast was just one of the missing pieces for me. I recently picked up a couple of tools from a garage sale from a man who did body work for 30 years. I told them that I was going to use them to make shoes.

I am assuming that I need to also compensate for the lack of toe spring at this point and remove plaster from the sole and add to the tops of the toes.

Will the plaster still be easy to work with (green) in the morning?

Geri
jask
2
2
Posts: 60
Joined: Tue Apr 15, 2008 11:30 pm
Full Name: jask

Re: Correcting common foot problems

#223 Post by jask »

just wrap the cast in a plastic bag overnight.
you will need to do a few things before you add the toe extension. Looking at the cast from behind you want to look at the angle of the heel.Draw a reference line with a pencil or lightly scribe with a knife, it should be centered on the bottom of the heel and extend up to the center of the Achilles-this may, or may not be perpendicular to the floor or the heel pad of the foot but should indicate the center of the heel (calcaneus) and allow you a reference for heel posting.
Looking from the front of the cast with the toes at bench edge- do all of the metatarsal heads touch the benchtop evenly ? you will probably find that in the corrected position the cast will have space under the inner metatarsal heads and this is the area you will be filling with footbed or orthotic to reposition the foot.
Let me know what you find and I can give you some idea how much correction to try. What materials do you have for this insole or orthotic? would you like to make a "fitter" orthotic to have him try out before you start shoe construction?
gshoes
5
5
Posts: 205
Joined: Thu Feb 14, 2008 10:41 am
Full Name: Geraldine Rabey
Location: Elgin, IL, United States

Re: Correcting common foot problems

#224 Post by gshoes »

Jask,
This is what I found. The center of the calcaneus bones have been marked. I will mark them better once you confirm for me that I am placing it acurately. The toes do not touch the bench evenly. Are they supposed to in a corrected possition?. When I casted the foot we used a 1/2" heel wedge. I placed a 1/2 piece of wood under the center of the heel. Is that correct or should I have it closer to the outside edge of the convex heel surface? With the wood under the heel the big toe almost touches the table. Do I need to take a measurement of the actual maximum toe thickness with a caliper before I grind off any of the bottom surfaces to give to spring?
ImageImageImageImage

Geri
gshoes
5
5
Posts: 205
Joined: Thu Feb 14, 2008 10:41 am
Full Name: Geraldine Rabey
Location: Elgin, IL, United States

Re: Correcting common foot problems

#225 Post by gshoes »

Jask,
This is what I found. The center of the calcaneus bones have been marked. I will mark them better once you confirm for me that I am placing it acurately. The toes do not touch the bench evenly. Are they supposed to in a corrected possition?. When I casted the foot we used a 1/2" heel wedge. I placed a 1/2 piece of wood under the center of the heel. Is that correct or should I have it closer to the outside edge of the convex heel surface? With the wood under the heel the big toe almost touches the table. Do I need to take a measurement of the actual maximum toe thickness with a caliper before I grind off any of the bottom surfaces to give to spring?
7912.jpg
7913.jpg
7914.jpg


Geri
You do not have the required permissions to view the files attached to this post.
Post Reply