CHAPTER I - Cabin & bubble canopy construction
To produce a thin-skinned, right-to-scale cabin, a solid rock one-piece
"image cast" of the bubble typed cabin should be made of modeling clay
& epoxy first and then try to reproduce a copy by vacuum forming the
image cast. Using the following modeling clay item, found in a
supermarket. It's an air-drying modeling clay ideal for scale modeling
and shaping. According to the instructions, it can be easily formed into
shape, become solid rock withing few hours, re-filled or sanded if
necessary and painted or lacquered. That sound quite good to me and
similar to the well known Milliput epoxy putty, with the only difference
that the 500g air-drying modeling clay pack cost only 1£, instead of
100g Milliput epoxy putty which cost 5£. That makes the new found
air-drying modeling clay, about 25 times cheaper than Milliput epoxy
putty and that's a good reason for me to give it a chance.
I formed the basic shape of the bubble typed cabin, by picking small
quantities of this modeling clay with a metal spatula and applying the
air-drying modeling clay. It felt too soft and very easy to spread the
material nicely. I didn't want to care too much and try forming and
shaping the clay, because I was planning to add epoxy putty and sand to
make a nice shinny finish. After all, I had no idea how much available
time I had, before the material start becoming hard and difficult to
handle.
The specific polyester filler I used to apply over the clay, comes with
the proper catalyst which provides a solid rock build and approximately 3
to 5 minutes time window to form it into shape. I prefer to use epoxy
putty or polyester filler with fiberglass grains for special purposes,
because:
- It becomes solid rock within only few minutes or seconds,
- it does not shrink and does not crack after months or years,
- you can pour to any shape that you want but you need to work fast
because as soon as you mix it with catalyst cream approx 5%, you have
limited time before becoming solid rock,
- you can also put additional layers of epoxy or polyester filler to build up,
- you can sand it, you can drill it, you can use any type of scale
modeling glue, any type of primer or enamel / acrylic paint on it with
no problem,
- can be purchased at any good crafts store into 250ml, 500ml, 1lt
(comes with a tube of catalyst hardener) or bigger canisters and if you
can't find it, fear not and try your local decent hardware store and
finally...
- it is cheaper than dirt - estimated prices are £3 to £10 depending
the canister size, the quality, if contains fiberglass grains for
maximum strength etc.
Keep in mind that the chemical reaction after mixing the polyester
filler with the catalyst hardener, produces some heat that possibly
effect on thin plastic parts, so test it first before try it on your
scale model. I don’t think that the produced heat is more than
Fahrenheit 110, but better watchout. Remember that epoxy materials are
dangerous when breath or shallow and could result skin, eyes or lungs
problems or even cancer when used for long period with no precaution
measures. Always keep in mind, that a powerful vacuum system to suck
away the epoxy dust should be used all time to keep the workbench area
clean while sanding or milling epoxy or resin materials. Using an issued
breathing mask and a pair of surgery latex gloves to prevent dust
contact with lungs and fingers while sanding or milling epoxy, is also
an important matter that you should seriously take care of! My
recommendation is to also wear an overall working suit (as I do) to keep
your clothes dust free while sanding epoxy. Some people might find it
too much, but I wouldn't like to bring epoxy dust & grains from my
work bench into living room and my beloved.
When the cast used as an "image" of the bubble typed cabin, was filled
with a layer of polyester filler and had enough time to polymerize and
get solid rock, it was sanded carefully to get the right shape. Finally,
the cast was sprayed with white shiny finish to help me spot any
scratches or defects.