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Old Jo-Han promo plastic question

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Posted (edited) · Report post

I've aquired an old 1960 Jo Han Chrysler promo that has a lot of damage. Is this some kind of strange plastic that can't be repaired or am I OK to start working on it?

Edited by Craig Irwin

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Posted · Report post

If it's the same as some of mine, it IS much more solvent-resistant than the current crop of 'styrene' model cars. I started re-building this '61 a while back...

DSCN5053.jpg

I had to use hot liquid cements like Tenax to get any adhesion. Finally ended up using a slow-cure epoxy and fine glass colth inside the body to keep it from re-cracking...

DSCN5966.jpg

But it's fine now, and on the way to a full recovery...

DSCN7592.jpg

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Posted · Report post

Those old JoHan Promos WERE molded in some weird won't glue plastic. That and the fact that the model KITS were molded in regular styrene makes the hard to find unwarped.

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Posted · Report post

Looks great! I've got part of the hood and right fender missing, nothing like you started with! It's not warped so I don't think it's that acetate (spelling?) stuff. I think It's a New Yorker but will be a 300 F.

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You're right...it's definitely NOT acetate, which would most likely be pretty badly warped by now. I honestly haven't tried CA on the old Johan stuff, but it's a possibility.

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Posted · Report post

You're right...it's definitely NOT acetate, which would most likely be pretty badly warped by now. I honestly haven't tried CA on the old Johan stuff, but it's a possibility.

Those older JoHan promo's prior to 1963 (and AMT promo's through 1961) were most certainly molded in acetate plastic (trade name TEnite), and for a very good reason: Safety. Styrene plastic in its early years was very brittle, and a styrene plastic toy, when dropped, could shatter very much like glass. Acetate plastic doesn't have that hazard as it is a lot tougher, more resilient. However, acetate plastic has a tendency to shrink after being molded, as well as being affected by humidity, which leads to warping of complex hollow shapes, such as a promotional model car body. For 1962 promo's, AMT switched to a then-new type of plastic: Cycolac, which was the early trade name for ABS plastic. JoHan made this switch for their promo's for 1963 (MPC came along a couple of years after the introduction of ABS.

Art

Acetate plastic can be glued though, just not with the cements we are used to using on styrene plastic. Revell and Monogram both produced their first plastic model kits in acetate, Revell marketing what they called "Revell Type A Cement", which was acetone based. In fact, acetone is the solvent for acetate plastic. However,while acetone will also dissolve styrene, it's the dissimilar molecular structures that prevent acetate and styrene from bonding with any strength with the use of solvent-based cements.

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Posted · Report post

You're right...it's definitely NOT acetate, which would most likely be pretty badly warped by now. I honestly haven't tried CA on the old Johan stuff, but it's a possibility.

Bill, not all acetate models warped--I've seen some, and have a couple that are still straight as a die It's been said that humidity has a part to play in that, which makes some sense, given that the straightest acetate promo's I've seen seem to have come from the desert southwest.

Art

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Posted · Report post

I have a buddy who has an old Chevy pick up promo that has warped down in the middle, providing a fairly realistic representation of what old Chevy work horses look like today.

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Posted (edited) · Report post

Bill, not all acetate models warped--I've seen some, and have a couple that are still straight as a die It's been said that humidity has a part to play in that, which makes some sense, given that the straightest acetate promo's I've seen seem to have come from the desert southwest.

Art

Thanks Art. That's very interesting. I should have been more clear. What I meant is that MINE is not acetate, at least not like any other acetate I've seen. I have some other acetate models and they don't behave or look like the plastic my '61 Dodge is made of. Based on your information, I did some more research on what I have and APPARENTLY both AMT and Johan kitted the '61 Dart. This one IS extremely brittle, as evidenced by the multiple pieces it had shattered into. Maybe it's an early styrene kit. Liquid glue for styrene WILL work on this old model.

I had assumed it was a Johan issue, as the molds I made from a resin-repop that was made from a Johan promo original (supposedly) fit my body perfectly. There was no chassis plate with the broken body-shell I got, so no identifying trademarks.

Do you happen to recognize the light-green mine is molded in as being either kit or promo ? I've seen these described as both on the internet.

Edited by Ace-Garageguy

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Weird part is, Promos were molded in Acetate but a kit version the same car was molded in stryene

Its not unusual to find a warped promo but a perfectly mint unwarped kit of the exact same car / kit / time period ( Johan 1963 Dodge Polara as an example )

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So hummmmmm...... Do I try to repair it or look for a 60 Desoto body to start with?

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If it's not warped, it's repairable with CA or epoxy.

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If it's not warped, it's repairable with CA or epoxy.

True, but I wonder if it will warp in a few years. I've got it so I might as well go for it and hope for the best. Thanks for the help guys!

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I have a 62 Studebaker Lark convertible Promo that needs a new windshield frame.

Not sure I want to try that work.

I though one reason for the Acetate was the High-Gloss the bodies/parts had without the need of paint

Also, isn't thickness a factor in warping??

I have a PMC 59 Ford Country Sedan wagon the though it has Shrunk, is still fairly Straight.

The interior has twisted though.

Both Hubley 60 Ford wagons I have, have the typical "Smile" effect of warping

I have done the Windshield replacement on a 63 Ford convertible promo. I had to add pins to get it to bond well though.

Might have to try a better adhesive.

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my gutt says if it's not warped by now, it's not going to .

If you want to find one of the original Johan 1960 thru 1962 Chrysler New Yorker kit's . open the wallet they get pricey and fast.

I occasionaly try to get a 1961 but would consider a 1960. but I'm not paying nearly a C note for a builder. Unbuilt ? is really gonna hurt

True, but I wonder if it will warp in a few years. I've got it so I might as well go for it and hope for the best. Thanks for the help guys!

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However, acetate plastic has a tendency to shrink after being molded, as well as being affected by humidity, which leads to warping of complex hollow shapes, such as a promotional model car body.

The proof:

warp1.jpg

warp2.jpg

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Thanks Art. That's very interesting. I should have been more clear. What I meant is that MINE is not acetate, at least not like any other acetate I've seen. I have some other acetate models and they don't behave or look like the plastic my '61 Dodge is made of. Based on your information, I did some more research on what I have and APPARENTLY both AMT and Johan kitted the '61 Dart. This one IS extremely brittle, as evidenced by the multiple pieces it had shattered into. Maybe it's an early styrene kit. Liquid glue for styrene WILL work on this old model.

I had assumed it was a Johan issue, as the molds I made from a resin-repop that was made from a Johan promo original (supposedly) fit my body perfectly. There was no chassis plate with the broken body-shell I got, so no identifying trademarks.

Do you happen to recognize the light-green mine is molded in as being either kit or promo ? I've seen these described as both on the internet.

Well, if the plastic that body is made from broke or shattered easily, chances are it's the styrene kit, not the promo. Also,acetate plastic gives off a bit of an odor when it's cut with a razor saw, unlike styrene.

Art

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Well, if the plastic that body is made from broke or shattered easily, chances are it's the styrene kit, not the promo. Also,acetate plastic gives off a bit of an odor when it's cut with a razor saw, unlike styrene.

Art

Thanks for the smell reminder, Art. I'd forgotten that.

And Casey, what a shame about that wagon. Looks pretty much beyond help.

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Thanks for the smell reminder, Art. I'd forgotten that.

And Casey, what a shame about that wagon. Looks pretty much beyond help.

I saw it on eBay, but have looked at many similar '60 and '61 Studebaker Lark promos. :(

One of the vintage Car Model mags I recently bought has an ad mentioning Cycolac, so I'll have to scan and post it.

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When I as a kid, I had one of the AMT Turnpike slot-car sets. I seem to recall those bodies were also Cycolac (ABS) and were tougher than the styrene kit bodies. The tooling was the same as the kits, as I swapped several styrene screw-bottoms that were the right length on to the slot chassis.

At the time, I didn't realize promos were even still made.

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So is it correct that acetone will be able to glue acetate together? I've wanted a '58 Chevy four-door hardtop for a long time, but they're always bent down at the tail. I think I could cut the body at the rear door line, do a pie-cut going up from the bottom and reattach it - if there was a way to cement the two parts together. Would acetone do the trick?

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I envy you guys that can correct a warped body... I have a few like that that Id love to restore one is the 59 Ford 4door wagon mentioned...another is a 60 Comet,59 Lincoln HT roof and others. I do know Acetone will glue/melt some plastics together just cant remember what types.

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old411s-vi.jpg

Did you say warp? My own understanding is that these warped within a short time after being made as the plastic off-gassed. I've been told that they won't warp any more. That's not to say that when guys try to straighten them out, that they won't go back. This '57 Plymouth body is so warped that all 4 roof posts broke and the roof is a separate piece now.

old116s-vi.jpg

And both of these Chevys are pretty warped. Note the roof on both, and the trunk lid on the '59 actually warped upward.

I have a bunch of these that were acquired as part of a collection. I'm not a promo collector and it actually bothers me to look at these! I'd much rather have more modern kits to represent these cars in my collection.

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So is it correct that acetone will be able to glue acetate together? I've wanted a '58 Chevy four-door hardtop for a long time, but they're always bent down at the tail. I think I could cut the body at the rear door line, do a pie-cut going up from the bottom and reattach it - if there was a way to cement the two parts together. Would acetone do the trick?

Acetone is the perfect solvent (or glue) for acetate plastic, always has been.

Some have asked why early 3in1 model car kits were made in styrene, while promo's were made (from very nearly the same tooling) in acetate plastic (later Cycolac --also known as ABS plastic): That's pretty simple.

Acetate was probably the very first plastic compound that could be melted with heat and then injected under high pressure into steel molds to make molded plastic parts. In the middle 1930's, acetate (known then by the brand name under which it was invented by DuPont: Tenite) plastics were used for many products, knobs and trim for home radios, knobs, and even dashboard trim for automobiles (Ford promoted their use of acetate plastic made from soybeans--one of the very first "biorenewable" plastic products!). Acetate's principal advantage (besides being the first injection moldable plastic) was, and is, it's relative toughness, and resistance to shattering.

After WW-II, along came styrene, which showed promise of being an inexpensive plastic material that could also be injection-molded. However, straight styrene is very brittle, shatters easily into shards that present a laceration and puncture hazard--particularly for kids playing with toys made from the stuff. So, when Cruver, AMT, Product Miniatures and Ideal Models (which later changed in name to JoHan) began producing promotional model cars for the auto industry, they quickly settled on the relatively shatter-proof acetate plastic. Anyone who remembers the very earliest plastic model car kits, particularly from AMT and JoHan, which body shells were molded in promotional model tooling, will remember just how brittle those bodies (and other parts) could be

Acetate however, has always had its drawbacks: It shrinks somewhat over time, as evidenced not only by warped promo's of the era 50-60 years ago, but also steering wheels (which were molded from acetate over steel structures) with rims that cracked into segments of plastic with gaps upwards of 1/8" all around the wheel rim.

In the very late 1950's, ABS plastic was developed. This material resists shattering very much like acetate, but doesn't have the shrinkage problem, nor is ABS affected by moisture (either from immersion in water, or merely the humidity in the air) that are also drawbacks of acetate plastic. It's little wonder that ABS quickly found a place in toymaking, and is still used to this day.

AMT Corporation made the transition from acetate to ABS with their 1962 promotional models, while of course retaining styrene for use in molding model car kits. JoHan made the shift sometime in midyear 1962 although their first full year of molding promo's in ABS seems to have been 1963. MPC, when introducing their promotional models for 1965, along with several 1/25 scale slot car kits, heavily advertised their use of Cycolac ABS for these products.

Art

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