Courtesy of Wally over on AMI
Many times an otherwise satisfactory kit is let down by poor window fit or moulding. The first kit this annoyed me enough to seek a way of fixing that was a Monogram1/48 C-47 and bolstered by the success of that project I went on to develop the technique with other models, some with near disasterous / almost write off consequences. I have been asked about the technique at various times on the various forums and whilst it is not rocket science you can get a good result with a minimum of fuss if you follow these steps and avoid all the pitfalls I discovered on my experimentation journey.
Basic Technique #1 Suitable for cabin windows where the window openings are such that they can be easily dammed (ie no humungous curves in the fuselage window area.1. First I used polyester resin, it did work but I had a number of failures...mainly I put too little catylist and it did not "go off" properly, I was left with a toffee like mess which softened and ate the plastic so I gave that up as a bad joke and went for two part epoxy casting resin.
2. Because we want clear windows we must use a slow setting "runny" brew so that:
- we can mix slowly, avoid and eliminate bubbles
- allow the mix to run into the cavity
3. Because it is so "runny" we must make good preparation to prevent the mix from oozing through gaps and holding into the desired area (the DC3s were easier to do because the windows are all level and in the same plane, the Hudson with its curved fuesage (tapering fore and aft) required "building of some "dams" around the window.. so if you are an interior detailer its not really an option for you unless you do 1 or 2 windows at a time avoiding building the dam... very wasteful of resin.
4. the resin is poured from the inside, so the outside fuselage surface, has to be protected from leaking AND has to incorporate a "wall" to hold the resin in the window cavity:
masking tape is not satisfactory in this role as it is not rigid enough and does not hold the outside "shape"
5 Fuselage preparation:
- rough up the interior walls around the window a little to ensure the resin "keys" (i always forget to do this and I have only ever had 1 window "fall through" inside when sanding)
- paint interior of the window frame the desired colour
- lay masking tape over (outside) the window areas allowing a large overlap (go to the very top and bottom of the fuselage half) note the masking tape serves 2 purposes
a) it protects the fuselage from leaking resin saving you clean up / sanding and it allows resin to sit the tape thickness "proud" of the exterior window level (this way you can ensure the resin fills the whole window cavity and you can sand it back flush to the skin.
- burnish the tape down hard into the plastic
- with a sharp scalpel blade cut out the window holes
you now have the exterior of the fuselage masked with the window openings cut out, next we must block the windows off to hold the resin in..we now prepare the "strip"
you make a strip from thin cardboard (actually thick paper is better, its easier to conform it to to curves) which you cover with cellotape, cut the coated cardboard strip big enough to provide a generous overlap over the window areas, note the cellotape provides:
- a resin proof barrier and
- allows a smooth interface between the resin and card board allowing it to be easily peeled off when dry)
Now my latest technique to reduce "leakage" (reminds me of a tampon commercial!) is to apply another layer, this time, double sided tape around the outside of the window openings (this helps to hold the "strip" down tight against the window openings.)
Next if you have a curved fuselage / window area pre bend the "strip" to the approximate shape, then apply the "strip" (shiny cellotaped side down) over the window holes, press / burnish the strip down hard into the double sided tape
Next apply masking tape over the strip, burnishing the tape down, doing your best to hold that strip down hard against the fuselage
the fuselage is now prepared for pouring..
Now you should ( I have never done this because I am hopeless)
- find a nice level area where you can let your fuselage halves rest for half a day while the resin cures
- set up some clamp / mounts so that you can hold the halves at the right plane to ensure:
- the resin fills all the window openings and
- does not flow out into unwanted areas
With this prepared,
make up your brew, stir / mix slowly do not introduce bubbles into the mix
fill the window cavities
- I use sprue to "drip" the resin into the "holes", try and flow it in from the side to avoid air getting trapped, either work bubbles out or prick with a pin (good luck with that!)
- if you want optically "flattish" glass pour resin so that all the windows are joined by a layer of resin, (if you just dollop the window individually you tend to create a "lens")
Set the fuselage halves in your preprepared mount (yeah right), level and braced, come back often look at the resin level and adjust the alignment to ensure the resin stays exactly where you want it, when it appears ok, leave it be overnight to set
When set hard, pull off the tape, then the strip, then everything else, wet sand windows coarse to fine polishing
now if you have rounded windows the next bit of fun is to mask the bloody things! in the words of confucius (Benny Hill) Rots o' Ruck wi' that
Technique #2 One for the masochist who wants a large clear view well fitting window in a complex curve situation eg light aircraft cabin window.
The principle is the same
except the paper strip is on the inside of the fuselage and the resin is poured in the holes from the outside. Due to the confined space and often complex curves and obstructions it is much harder to a have a well conforming paper strip dam wall, I bolster this with a a backup of a large wad of modelling clay, this helps hold the strip hard against the windows and helps reduce leakage. Also for this you must make a dam or reservoir to hold the resin in the area and requires a lot of sanding when hardened. the pictures tell it all
