I have gotten a lot of questions about how I use this illusive material known as Expanded PVC Foam Board, which I just call Sintra (which is a brand of this product). I tend to talk a lot about the subject and just how much I really enjoy working with it. Because I want to be sharing this on Deviant Art, rather than on a blog, I’ll be breaking my tutorials down into sections.
These tutorials will not be going over use with any power tools, since I don’t have any. I will be doing everything by hand, using manual techniques. The only power tool I own is a small hand dremel which I don’t use often with the Sintra, except for drilling holds, etc.
Before I begin, I want to start off by saying that Sintra, when heated, releases toxic fumes like many other plastic products. I do not recommend heating this product in an oven which is used to cook with, and also take care about heating it in doors in general. There are some methods you can find with good old Google, which describe ways to reduce the amount or potency of the fumes. But let it be known, you are working at your own risk with these fumes in your house.
Ok on to the fun stuff…
Figure 1: Lan Fan's Chipped Armor. Notice that the white plastic below shows easily when the paint is scratched or damaged.
These are the two issues you’ll be dealing with in choosing your Sintra. I’ve only ordered white and black in the past, but it does come in a variety of colors. This may be useful to some degree, but in most cases you’ll be covering the whole product in primer, so it will only matter if it gets chipped down past any paint or primer.
I began with sheets of Black Sintra, but by mistake I was sent a bunch of White on my last order. I originally thought it felt softer and easier to cut, which also translates to less stable and more flimsy. However, after looking it over, I retracted that thought. Even if it is easier to cut, the final product quality is still the same despite the difference in color.
Figure 2: Uneven edges.
Size or Thicknesses:
I’ve worked with two thicknesses, and my main reasons are based on Cost. The thicker the Sintra, the more difficult it is to cut and the more expensive it is. And when I say difficult to cut, I mean it. It takes more than twice as long to cut ¼” Sintra, than it does 1/8” Sintra when cutting by hand. It also leaves a lot of room for error on edges, because as you are cutting there may be slants along the sides, which make it more difficult to line up layered pieces.
When you order your Sintra, from my experiences, I’ve needed to ask for my sheet of (4 x 8) to be trimmed down into four 2x4 sections, which are then shipped to me. In most cases, you may need to order more to make their “minimum price”. I’ve gotten my ordered, trimmed and shipped to me at an average cost of ~45.00 for a 4x8 sheet of 1/8 Sintra. You can get it cheaper than this, but with shipping included on such a large product, that isn’t too bad. And 4x8 lasts a while. You’ll need to work with your distributer on this to see what works best for you.
Figure 3: An example of the types of tools I keep on hand for working with Sintra.
The great thing about Sintra is that it tends to be a fairly self sufficient medium to work with. When I say that, I mean that you can get a finalized product with Sintra without using other overlays to get a smooth exterior (like gesso or friendly plastic). But you still need to have tools to work with the product, so here is what I normally keep on hand:
I normally go with about 220 with a standard household oven, but at this temperature you don’t burn the Sintra, and get nice even coverage. The Sintra should be malleable within a few minutes of placement in the heating unit.
Not really. I don’t like how heat guns give very uneven heat distribution. It is much easier to heat the pieces in an oven or heating unit. Heat guns are only used to locally modify a portion of an already molded piece. For when I don’t want to remold the entire piece, or if I have already assembled and want to modify a small portion of the piece I am working on.
At these low temperatures the Sintra will not burn, even when left in the heating unit for an extended period of time, and will remain ready to be molded. So adding a few pieces of Sintra to the oven at one time isn’t going to hurt them, but it will release even more fumes. The same goes for large pieces of Sintra.
Figure 5: Here's a few pics of me trimming down a large sheet of sintra.
Figure 6: Cutting out a template piece. Sorry the images are sort of blurry.
For thin pieces, just scoring may have been enough to cut through the sheet of plastic. However, if you are using a thicker sheet, or maybe the line is shorter or curved, so you can’t cut as deep as easily:
And that’s it for the basics!! Next I’ll be going over how I fuse together the pieces which were cut out, molding them with heat, and how I pretty them up!