Can you melt clear styrene and then form it?

[Robert Porter]

Can I melt clear styrene, like the see through sprue etc, and then form it into a shape and will it be clear? Just curious if anyone has ever done or tried this to make a small lost part or in my case one that I really messed up.

 

[GrauGeist]

You can try, but some styrene may discolor if it reavhes a certain temp.

One of the best methods to heat styrene is with a hot air gun (or the misses' hair blower - when she's not looking) and heat it slowly to the point of being pliable.

If it heats too quickly or overheats, it may bubble, discolor or both.

 

[mikewint]

As I posted a while back, I'm not a sprue stretcher...but, heat is not the only way to "melt" styrene plastic. Get a glass jar with a metal lid. Fill 3/4 or so with acetone. Drop in your sprue pieces and wait several hours. They will "melt" into a puddle of goo at the bottom of the jar. Remove the goo lump and you can now stretch, mold, and shape easily by hand. The goo lump will remain flexible and moldable for several hours but it will eventually harden as the acetone evaporates. Never tried this with clear but it does not alter the color other non-clear styrene.
As to thermal heat, styrene's MP is about 250F or so. Thus a heat gun, toaster oven, or hair dryer will easily soften it. As to a possible alteration in clearness I would suspect that keeping the heat down would avoid that. After all the parts were thermally extruded into the molds to begin with at the factory

 

[Airframes]

The basic answer is 'No'.
The clear parts in kits have a different composition to the 'solid' polystyrene parts, and may not even be styrene.
Heating the clear sprue, for example, will allow it to be bent, but forming a part is very unlikely. Also, the clear parts will deform more quickly, compared to stretching 'solid' sprue, and are very unlikely to remain perfectly clear once heated. Stretching clear sprue to make such things as rigging wires, however, works quite well, bearing in mind it softens quicker.
You can mould parts, with heat, using clear sheet (which is normally acetate), available in various gauges from most model outlets.

 

[Robert Porter]

The basic answer is 'No'.
The clear parts in kits have a different composition to the 'solid' polystyrene parts, and may not even be styrene.
Heating the clear sprue, for example, will allow it to be bent, but forming a part is very unlikely. Also, the clear parts will deform more quickly, compared to stretching 'solid' sprue, and are very unlikely to remain perfectly clear once heated. Stretching clear sprue to make such things as rigging wires, however, works quite well, bearing in mind it softens quicker.
You can mould parts, with heat, using clear sheet (which is normally acetate), available in various gauges from most model outlets.

Dang, it was worth a shot, since I save all my sprue I have quite a bit of clear sprue and was hoping I could do something with it to scratch build or replace parts. Yet they would remain clear.

 

[Airframes]

What parts to do you need to make Robert ?

 

[Robert Porter]

What parts to do you need to make Robert ?

I more or less melted with glue one of the landing light covers on my B-17G Revell kit. It is the ones that go in the leading edge of the wings outboard of the engines. It's very small.

 

[GrauGeist]

So what you need is a small, flat (or curved in relation to the wing's leading edge) piece?

 

[Airframes]

Ah, I see !
I know the part you mean.
It might be possible to form one from clear sheet, or, alternatively, if you have a piece of clear sprue that is thick enough, this can be glued into the recess using poly cement, and then filed and sanded to shape. It can then be polished to a high shine, using metal polish, or better still, car body colour restorer (T-Cut is a UK brand), and then given a coat of future.
The finished lamp cover might not be as good as the original kit part, but it'll be better than a gaping hole in the leading edge.
If it comes loose due to the sanding, it can be cleaned up, and fitted back in place using PVA or clear canopy glue, which will not 'fog' the glued areas.
I once made some similar lamp covers, by using the clear shaft of a ballpoint pen, sawn down the middle and cut to shape. It didn't quite fit along the leading edge but, once polished, the small gap was filled with PVA and painted, making the 'lens' only very slightly smaller, but it worked, and looked fine.

 

[GrauGeist]

I might also suggest looking around the house...there are several sources of clear material that may do the trick, such as old CD or Cassette tape cases, for example.

 

[fubar57]

Empty clear pop(soda) bottles as well. Squadron used to make clear sheets but I've read they quit making them. But wait......there's more

squadron plastic Model Scratch Building Clear Sheets

 

[mikewint]

Terry, can't speak from experience heating or bending clear sprue but those clear parts were at some point thermally extruded into molds so why would further gentle heat cause them to cloud?

 

[GrauGeist]

In all seriousness, I think it falls into a molecular level, Mike.

Styrene alters it's state if manipulated, like colored styrene becomes "whitish" if you bend it and the clear styrene becomes either cloudy or has a "rainbow" effect to it if it's bent.

When the material is in a liquid state and then injected into a mould, it's physical state is set and manipulating it after that runs the risk of upsetting that state. I have been successful in the past, by slowly heating the clear with a heatgun and getting it to the shape I was looking for, but if I overworked it, it would become cloudy - it's sort of a one-shot deal. Heat it into position and leave it alone, if that doesn't work, start over again!

 

[mikewint]

Dave, that's what I expected which is why I said "gentle heat". Boiling water at 212 would be close to the MP. The white bending effect I suspect is due to super fine cracks forming at the bend
And I prefer the acetone "melt" to heat any time

 

[Robert Porter]

So what you need is a small, flat (or curved in relation to the wing's leading edge) piece?

Exactly!

 

[Airframes]

Mike, Dave has more or less hit the nail on the head. The problem trying to apply gentle heat, is controlling it - it's very easy to overheat, when the clear material will either cloud, or bubble internally, or both. It's a very hit and miss situation, outside of a factory or lab environment.

 

[Crimea_River]

You could consider making the part with a clear 2 part resin available at any good craft store. I made this P-38 engine cowl with this method. The part is quite large so has some imperfections and loses clarity with thickness but for a small part like a landign light lens, it would look quite convincing.

 

[Robert Porter]

I have never worked with epoxy and casting, but I can make a mold from the original part easily so I suppose that would be fairly quick! I think Hobby Lobby carries the stuff I would need. I will have a look tomorrow. I may try a melt and mold just to see how it goes. Be fun to try anyway, as long as I don't get a glob on me and end up dancing around the kitchen hollering!

 

[parsifal]

It looks very difficult to me.

My guess is that melting the clear outright would almost certainly cause a reaction in the plastic and its clearness affected.

It might be possible to bend an existing part slightly with the application of heat, but boy, you would want to test the theory first.

I don't know how many kits I have messed up because I didn't respect the clear parts correctly

 

[Airframes]

You could, of course, mould a lamp cover, using the heat and 'plunge' method, with clear sheet.
It's fairly simple, but the preparation is a bit involved.
The PDF below, which I recently prepared for one of our members for moulding canopy blisters for a large-scale PR Spitfire, shows how it's done.
The balsa wood male mould could be replaced by a mould formed from Milliput, which could be shaped on the wing of the kit, then removed before fully set, an polished when hard.