I recall that someone mentioned using “melted” styrene parts tree plastic as a void filler material. I am not sure if the melting was effected by heat, such as a heat source under a metal spoon, or by using styrene glue or another adhesive medium. If anyone does this in their benchwork, please let me know the best (and safest) method.
Cedarwoodron
I do this and use MEK as a solvent to melt the plastic. Do not use lacquer thinner–the styrene doesn’t really dry, and will shrink weeks after finishing your model. Don’t ask me how I know this [:-^]
Greg
Yeah, no heat! Best to use to make it is the plastic from the kit you’re working on. Any shavings, sprues, dust from sanding and filing, it’s all th same once dissolved by the solvent. I use whatever’s handy on the bench and prepare it according to the size of the hole. To fill a big hole, I’ll take a chunk that’s slightly smaller, shape to fit, then soak it in the solvent until it softens, then place it. This is a little easier to control than making a paste is sometimes.
Is acetone (nail polish remover) applicable for “melting” styrene plastic as well?
Cedarwoodron
I use whatever solvent I am using for the rest of the model. But if it softens then evaporates it could be used. I think something known is better, because who wants to damage a model you’ve spent a lot of time on with uncertain results?
I’m curious why you’d want to fill holes in your benchwork with styrene. To fill holes in styrene or wood, the best filler is a similar material: wood for wood and styrene for styrene.
I’ve used lacquer thinner for years to cement styrene or to make a filler putty from styrene scraps and shavings, and have never had a problem with the filler shrinking. However, a better way to fill holes in styrene is to use solid styrene.
Use a suitably-sized drill to enlarge the hole to be filled so that it’s about .005"-.008" smaller than an available size of styrene rod. For instance, if the hole is .068" in diameter (or .068"x.068") use a #48 (.076") or #49 (.073") bit. Use a small brush to coat the inside of the hole and the outside of a short length of .080" styrene rod with solvent-type cement. Wait a few seconds to allow the surfaces to soften, then jam the rod as far into the hole as it will go. Allow the joint to fully cure, preferably overnight, then use a sharp #17 or #18 X-Acto blade to slice off the excess material. No further filling should be required.
You can do something similar in wood, using dowelling and carpenter’s glue, although the hole should be the same size as the dowel.
I also used styrene to plug holes in an old Varney metal boxcar. The holes were first drilled out, then contact cement was used to add pieces of .060" sheet styrene behind them. The holes in the metal siding were then extended through the styrene. The holes were then plugged with styrene rod, as outlined, which was sliced off flush with the metal sides. New holes for grabirons were drilled where needed, and short lengths of strip styrene were cemented to the exposed ends of the plugs wherever needed for adding l
Wayne- (LOL) I meant filling voids/holes in the model’s surface, not my benchtop table surface![:D]. I have used the solid styrene rod procedure, where I drilled out the hole to the same diameter as the rod and carefully cut, then sanded the hole flush with the model’s surface. That works for some holes that you want to eliminate, but- when I pick up swap meet beauties that I want to recondition, there are other irregularities which may appear in the plastic surface that are not conducive to the “plug and sand” method.
If I use Squadron putty or even Bondo, the subsequent material shrinkage (after allowing the filler to dry and then sand and re-fill and sand again) often presents a visible blemish on the model’s surface that no amount of sanding with progressively finer grits (1000-1500-2000, for example) completely eliminates. I only find this out when I primer paint that surface and see the “filled area” once more visible underneath the primer coat. I have then tried to use a thicker sprayed top color coat, reasoning that the additional quantity of paint would “level” the blemish and hide it, but this rarely works for me. My thought is that the use of the melted plastic as a filler medium would bond more naturally with the existing surface and then be more amenable to flush sanding.
Cedarwoodron
I have never tried to melt styrene plastic to fill holes, voids, or cracks, but I have used 2-part epoxy (JB Quik Weld) with complete success. Easy to form, easy to sand or file, no traces left once painted.
Rich
I prefer to avoid the fumes and use testos putty.
Sorry i meant testors putty.
For years I have used shaved styrene and MEK in a fume hood.
Rich
Sorry for the misunderstanding. [:)]
I’m not overly fond of the commercially-available fillers, as most of them dry too quickly. Auto body repair stuff (the ones which use a catalyst) can work well, but I have experienced problems with some of them damaging the plastic. Ideally, the filler would be applied where needed, swiped-over once with an appropriate tool - plastic card or putty knife-type of tool - then allowed to harden. That should leave a surface requiring little or no sanding, although an additional coat of filler may be needed. Most of us try to “work” the surface too much in an attempt to get it done in one application, when it’s usually wiser to walk away and come back later for the next step.
The problem with fillers made with styrene scraps and solvent is that they’re very aggressive on the surface to which they’re being applied - you need enough solvent in the mix to react with the surface on which it’s applied in order to get a strong bond. You may fill the previously damaged area, but create further damage on the periphery of the repair.
Automotive spot putty may
I, too, started using JB Weld and JB Kwik as filler ~10 years ago and I’ve never looked back. Dries plenty hard with zero shrinkage, and is very easy to sand and/or carve (if necessary).