Nice and should work. This medium has been used in the craftsman level of model railroading, though I don't think on the scale you are setting out to attempt. I'm guessing it should work out okay since it sounds like you are using a "dry toothbursh" method of application. I think the real challenge might be sealing the final product without damaging the inner core styrodur. Guess that means brush on sealer. I, too, wonder how the long term hold up will turn out.
Exactly right, model railroaders used this technique for years. Your product may be different from what is available in the US. Shoe polish in the US is usually alcohol based which means that if you intend to seal it with a spray-on enamel based matt coat make sure its really, really dry or it will frost. I have pulled a response on one of my model railroad forums that might provide some insight.
This was written by Craig Bisgeier, you can find his model railroad website at:
http://www.HousatonicRR.com I highly recommend taking a look at his site.
"Actually most if not all shoe dyes are alcohol-based, since water affects the
leather surface of a shoe poorly.
Having now used alcohol shoe dyes extensively for scenic work, i can recommend a
few things about it:
A little bit goes a LONG way. It is highly saturated with color straight out of
the bottle, and for our purposes (wood stain) it needs to be diluted -- a LOT.
Start at 1:20 to 1:50 dye:alcohol mix if not more.
I had a couple of fresh 6 oz. bottles of dye, one black and one brown, when we
got started dyeing the stripwood for my pier. I asked a friend to start working
on the dyeing before I was able to mix the proper stain strength, and he
misunderstood my instructions. Long story made short, he mixed both bottles of
dye with a quart of 70% rubbing alcohol (about a 1:3 ratio) and it was like it's
strength wasn't even touched. We have enough dye now to finsh my pier, every
piece of stripwood I'll ever place on my layout, and everyones elses' piers in
my local modeling group (at least three piers). We won't be running out anytime
soon.
We use a number of different dye application methods; brush, soaked paper towel,
catton balls. Brush and paper towels seem to work best. The brush is faster
but paper towels are best when you need a lot of control. You can also just
dunk the stripwood in the container if thet strips are small enough and blot
with paper towels. I use a wire drying rack to let the strips dry on overnight
after dyeing. Cotton balls are poor because they leave fluffy stained bits on
the edges of the stripwood. But sometimes they are good for dabbing spots.
Oh-- hey, use rubber gloves and a smock, this stuff even when diluted is a major
staining force, it will soak right into your hands and clothes and can't be
washed off. You'll thank me later.
It can be hard to find but most shoe repair stores carry it or can get it.
Problem is there aren't many shoe repair stores around anymore.
For me, the stain wasn't really enough, I needed to hit all my stripwood again
with a very light wash of gray acrylic craft paint (Delta Ceramcoat) to get that
weathered gray color onto it. Applied pretty much the same way as the dye, it
goes on very thinly, and you have to stop before you think it is right because
it lightens and becomes more opaque when it is dry. The delta paint is thinned
with water, not alcohol.
Hope this helps."
Craig Bisgeier
Clifton, NJ