First experiment with casting of gelatin/glycerine tires

[viejoronnie]

I was experimenting with a mixture of unflavored food grade gelatin/vegetable glycerin for use as a substitute for silicone material for use in slot car body molding. I had looked at dozens of different mixture formulas and came up one that seemed to work really well. It created a firm yet flexible molding material that maintains its integrity even at elevated temperatures.

Its physical appearance is that of a silicone or urethane rubber as far as density. It is very grippy, e.g. if I simply drag it across a clean glass surface, it grabs the glass as I do so and does not slide easily.

Has anyone played with this stuff to create their body molds or tires?

I acquired an extensive set of 3DP 1/32 tire molds from a pal on another forum and cast my first pair of what I am calling “gelgies”.

Testing to be continued on my home plastic track.

[HO RacePro]

Viejoronnie I think you may have come up with something unique. In nearly 60 years in the slot racing world I have never heard of anyone using gelatin to mold tires.

Gelatin is primarily made of collagen, a biologic material that is found in skin, fingernails, bones and tendons. It is highly hydroscopic -- it absorbs water -- and just how moist it is has a major effect on its properties. Dry collagen is hard and brittle. Moist collagen is flexible and gummy.

I would expect your 'gelgies' to be very sensitive to how much moisture they contain. As they dry out I'd expect them to shrink, become hard, and lose their grip. Too much moisture should dissolve them.

Coming up with a way to maintain the proper level of moisture may be a challenge. You may need to store them in an enclosed environment -- possibly including a source of humidity. You'd put them on only when you're ready to race.

It may be possible that the stickiness of the tires might degrade during a race, while exposed to a dry environment. The humidity on race day may be a factor!

It would also be interesting to discover how fast your 'gelgies' would wear. That might also be affected by humidity.

Collagen is a very tough, flexible material. We are not talking about Jell-O here. The whole concept is fascinating. I'll be very interested to hear about your developments and testing.

Ed Bianchi

[Kevan]

This will be more interesting once track time feedback comes to light.

[viejoronnie]

I am still experimenting with the formulation. As it stands now the formulation is excellent as is for a molding material for slush repopping of hard plastic bodies.

For tires I am adjusting the moisture content by replacing the 20% water component with up to 20% black acrylic paint which contains water, liquid acrylic, and pigment, to get a more stable material.

When I was making the original molding material I noticed that mixing the glycerine with water and then very slowly allowing the gelatin to dissolve in that liquid mixture using a salt shaker was preferable to just dumping the gelatin into the liquid mixture or mixing the gelatin in water prior to adding that slurry to the glycerine.

I have set out several sets of tires in the sun to dry for a few days and see how they fair.

An interesting project for sure.

I have a 4’ diameter skid pad made from some ancient 22 1/2 degree banked Eldon track to do some extensive track testing.

I suspect the tires will pick up dirt and dust from any track very quickly.

[viejoronnie]

Today I made a small batch of “gelglie” tire material substituting the full 20% water component with undiluted black acrylic paint. I mixed this thoroughly into the glycerin then slowly added the powdered gelatin and mixed until dissolved.
The resulting material appears to be much more resistant to potential degradation due to moisture or lack thereof.

[viejoronnie]

Extensive testing will answer performance/durability of the tires.

I will mount newly cast/cured and trued tires on the rear wheels only, measuring the beginning tire width and OD. I will start with a one hour test run at the maximum constant track voltage at which the test subject slot car can maintain itself in the slot. After 1 hour I will inspect the tires for wear/damage, remeasuring the tire width/OD. If the tire is not damaged/overly worn and has retained 85% of its width and OD, I will continue the test for several more hours (up to 24 hours), stopping the test run periodically to inspect/measure the tires.

Here is my tire test track.

[Frank9129]

I can't wait to find the results.

[SpeedyNH]

what brand of track?

[viejoronnie]

That would be the track from the “island of misfit slot toys” Eldon Industries, Hawthorne , California, ancestral home of The Beach Boys.

[SpeedyNH]

cool. thanks

[viejoronnie]

Trying my hand at making double sided gelglie tire using the plastic tires from my AMT Chapparral curbside kit as mold masters. went to Lowe’s/Home Depot for some slot car tire molding equipment. Now where’s that cork borer?

[dw5555]

Too funny. I like it.