Best clear plastic??

[abledog]

Hi all, years ago I wanted to make a better canopy for my old MPC Slave-One. Someone recommended a clear styrene, (I believe) and it looks great. At the time I had to use a technique where I heat it and pulled it over the master.

I now have an old Mattel Vac-form toy I'd like to use for this and would like to buy some sheets I can cut and drill to work with it. Now am I correct that it's simply clear styrene plastic, or was there a better one and I just forgot what it was called?

[Rocketeer]

A lot of the model airplane guys use PET, I understand; never tried it myself.

[naoto]

I've been using clear plastic found on "blister pack" packaging -- granted, I'm generally not building anything larger than "walnut scale" (around 16"~18" wingspan), leaning more toward "peanut scale" (11"~13" wingspan) -- yup, these size classes are essentially "box scale" -- if the subject is a WWII-era fighter planes, "walnut scale" ends up being around 1:27 scale, and "peanut scale" around 1:36 scale. As I never got around to getting a vacu-form rig, I've been mostly using the "plunge forming" (aka "heat-n-mash") method (and since I've been sticking to relatively small scales, the canopy parts are relatively small).

[jpolacchi]

Acrylic is "hands down" the best clear plastic,but its a bit if a chore to vacuform it.

[seam-filler]

The clear plastic used in blister packaging is usually PVC. These often have moisture barriers consisting of a film of PVDC (Polyvinylidene chloride) or PCTFE (Polychlorotrifluoroethylene). Get the temperature for thermoforming wrong and these added layers can cloud.

Blister packs for pharmaceuticals are usually (PP) polypropylene, PE (polyethylene), or PETg (glycol-modified polyethylene terephthalate) multi-layered with COC (cyclic olefin copolymers).

A lot of the model airplane guys use PET, I understand; never tried it myself.

Actually, they're using PETg - PET is opaque and is a b*gger to thermoform.

PVC and PETg tend to yellow over time, but significantly less than polycarbonate (the old go-to clear plastic). Polystyrene, ABS, acrylic and perspex are by far the clearest and least likely to yellow but require a much higher temperature to thermoform.

Personally, I use polystyrene or PETg from fresh stock - I almost never re-use plastic from a blister pack.

[naoto]

... Personally, I use polystyrene or PETg from fresh stock - I almost never re-use plastic from a blister pack.

[shrug] The re-use of blister pack plastic is mostly as a cost-cutting measure, and generally only used on relatively small parts. Other source of scrap material include CD jewel cases (mainly for flat pieces). Still haven't gotten around to see what I can do with those "blanks" that are the ends of the spindle-packs of CD-Rs and DVD-Rs (up until not too long ago, was going through 100-packs every couple months for backup purposes, so I did end up with a big stack of these "blanks")... Have been using the base and spindle from the "cakebox" packaging of optical discs as "quick-and-dirty" stands for my model rockets.

[seam-filler]

If it suits your purpose - fine. However, I find that blister packs often end up with a grainy look and aren't all that clear. But, as you say, you're often working with smaller canopies where it might not matter as much. But I do stand by what I said when I warned that the additional coatings (if present)can go cloudy when re-heating blister pack plastic. When you work with second hand material, you just can't know exactly what you're working with.

But then again, failure with second hand stuff won't have cost you anything but time & effort!

abledog asked for the best - I gave my opinion.

[jpolacchi]

Excluding "styrene" Allot of these "clear plastics require some "preheating to bake out what warer content there is in them so they don't cloud up/frost over or blister internally destroying their clarity.

[naoto]

speaking of polystyrene...
https://www.smithsonianmag.com/science- ... -36715644/

[abledog]

A lot of the model airplane guys use PET, I understand; never tried it myself.

I'll have to investigate that one. I want something that I can use the same as what I did with the canopy for Slave One.

I plan to make some in whatever shape I desire and, as good as the blister pack idea is, I'd find that extremely limiting for my purposes.

[abledog]

I found it! After a bit of digging I saw the name of the stuff I used... Lexan .030 thickness.

https://www.hobbylobby.com/Crafts-Hobbi ... 22/p/97972

I'll have to share a pic of the Slave One canopy I made years ago.

[jpolacchi]

You have to "pre-heat" and "cook"Lexan/polycarbonate for a while otherwise it will bubble and blister on the inside.

[abledog]

You have to "pre-heat" and "cook"Lexan/polycarbonate for a while otherwise it will bubble and blister on the inside.

I'll admit that it's been years, but I don't remember having to do that. I could be very wrong... (like I said, it has been years). I just remember liking the final product.

What about just plain clear polystyrene? Is that what after market manufacturers use for making canopy's for WW-II & modern aircraft kits? Do you know of any potential issues with this material?

I just re-read your comment about acrylic. I might have to look into that too.

[Zubie]

You might find this article helpful from IPMS stockholm
https://www.ipmsstockholm.org/magazine/ ... nopies.htm
it recommends PET-g over clear PS sheets (#6) and definitely against blister pack plastic mostly on being hard to work with due to it being optimized for industrial use with calibrated equipment as opposed to home use with a DIY heater or other simplified equip.

[seam-filler]

What about just plain clear polystyrene? Is that what after market manufacturers use for making canopy's for WW-II & modern aircraft kits? Do you know of any potential issues with this material?

Polystyrene needs a bit more heat than PETg - that can be hard to control in the home environment, because too much heat will cause it to darken and blister.

[aussie cylon]

You might find this article helpful from IPMS stockholm
https://www.ipmsstockholm.org/magazine/ ... nopies.htm
it recommends PET-g over clear PS sheets (#6) and definitely against blister pack plastic mostly on being hard to work with due to it being optimized for industrial use with calibrated equipment as opposed to home use with a DIY heater or other simplified equip.

Very interesting and helpful article. I might just try it. Thanks Zubie

[naoto]

You might find this article helpful from IPMS stockholm
https://www.ipmsstockholm.org/magazine/ ... nopies.htm
it recommends PET-g over clear PS sheets (#6) and definitely against blister pack plastic mostly on being hard to work with due to it being optimized for industrial use with calibrated equipment as opposed to home use with a DIY heater or other simplified equip.

Admittedly I've been using rather low-tech heating methods (involving open flame) that is indeed a tad fiddly and generally only suitable for rather small sizes. Heck, if all the materials (other than the plastic) was limited to bamboo and palm leaves, you'd think I was living on Gilligan's Island.

[seam-filler]

FIW I use an electric paint stripper gun. Used at about 10 to 12 inches away, a wide nozzle, a fairly rapid sweeping motion, somewhere safe to dump the gun as soon as the plastic starts to sag and a good pair of heat resistant gloves it is tricky, but the results are pretty good. Admittedly, a second pair of hands can be useful & safer.

Anything over 0.75mm (30 thou) thick gets tricky, especially with polystyrene or acrylic.