Refenestration: Adding windows to 40K terrain

Charlie: We’ve all imagined having actual glass in the tiny plastic windows of our ruined dollhouses. What a fun idea! How utterly impractical! The idea is sensibly consigned to the most conceptual of wishlists and left there to rot next to concepts like successfully painting one’s entire backlog. But in the distant, mist-wreathed valleys of Snowdonia, there is a man - well, a collection of 52 caffeine-addled squirrels in a trench coat with the name of a man - who wanted to know: just how does one make stained glass windows for 40K ruins?

That squirrel collective is the lovely Boris, one of the most far-flung members of our gaming group. At any given moment, one of the squirrels can have an idea that sets off a hyperfocus cascade. In today’s guest post, he is here to explain what he did and how he did it. We are not asking why he did it because the answer will be a sleep-deprived eye twitch and a giggle. We are simply here to enjoy and understand the fruits of his labours.

Boris: I am humbled to have my own work featured here alongside the outstanding and inspiring work of the absolutely magnificent Beard Bunker members.

How did we get here? Well, I blame it on what Charlie has referred to as being my hobby superpower: yeeting myself out of comfort zone. 

Risky? Yes. Worth it? Totally.

So there I was with a Battle Sanctum in the making, thinking: “I wonder what those ruins would have looked like with the stained glass still in them…” That was a ‘dangerous thought™’. Cue looking at ways to make it happen. Whilst doing so, my eyes glanced over the fully prepared but unpainted model of the Vindicare Assassin in the Saint Celestine bust… and I now new where I could mount that… 

Now who in their right mind would take a hard to get Battle Sanctum and a limited edition miniature of an iconic unit, and alter them both with techniques one is just about to figure out how to use? 

All my brain squirrels went “WHEEEEEEEEE!”. Which brings us here. 

Note: This is still no reason why I did it. I don’t know. The gods rolled dice and things happened, I guess…

I have broken up the “how the heck was that done?!” into separate sections which will hopefully explain the process well enough to enable anyone mad or brave enough to try it.

Materials & equipment

The materials for this are very simple, as is the process, once you know how it’s done (very much like catching bullets with your teeth, or so I’m told).

The materials needed

• Some sponge or, even easier, a foam inset from your transport case (which is what I have used) 
• Cling film (or you can experiment with specific resin foil; more about that and the limitations I found later)
• Resin, precoloured (I used JDiction UV resin. Please note that the colours might be paler/lighter than you anticipate them to be. The little dropper bottles are grand for this use.)
• Resin, clear (Vida Rosa UV Resin - I really like this stuff. It makes great water effects too).
• A UV curing lamp (please note that there are different types of UV lamps and not all have the correct wavelength for curing resin). I used the DARKBEAM UV Torch with a  395nm light frequency. My larger light is the ISTOYO UV Light)

PPE needed

• Goggles, ideally 100% UV filtering - because UV curing
• Disposable nitrile gloves (get the proper size, or they will rip and fatigue your fingers)
• A filtration mask. It depends on the resin you use, how well-ventilated your workspace will be, how exciting you think “popcorn lung” really is, etc., but I prefer using a proper ABEK1P3 filter mask. For obvious reasons, I cannot make any statements about what filter you might need - please read up on it; there are easy-to-understand charts available like this one: Filter Guide). 

Please note that any materials and tools you use with resin must fall into the “potentially disposable” category. So please don’t use the sponge inset you definitely and urgently need to hold your warlord titan in place in your transport case…

Overall budget

Excluding a mask/filter and gloves, which I already had anyway, you can probably do the whole building shown here (and then some, as there is a lot of resin left over) for about £45, including buying a roll of cling film, the UV lamp, and the resin of your choice. This obviously does not include the price of the model. 

Whether it is worth it lies in the eye of the beholder. As far as I am concerned, the learnings that have occurred on the way plus the end result made this a very worthwhile project and money well spent.

Making the windows

When the scurry of squirrels that is my brain decided that this Battle Sanctum project was “go” (I had no say in it, really, they tend to get what they want or take it by force…), I was wondering how to make actual stained glass effects.

The idea that came to mind was that I needed a substance that I could - somehow - inject into the existing window frame. I didn’t want to try cutting fitting plastic inserts, etc., mainly because I lacked the patience. My first try was with water effect gel, which also works really well, but it takes a long time to harden and does not cure hard, but somewhat rubbery.

So UV curing resin was the material of choice, as it is - with the right PPE - easy enough to handle and cures nearly instantly.

Preparation of the window frames

Technically, no preparation is required like wiping down with cleaners or anything, which is nice. HOWEVER… you need to apply the resin to fully painted terrain; otherwise, the unpainted bits of the window frame WILL shine through the resin and are near impossible to fix later. So, clean off the mould lines, prime and paint the terrain, and You’re good to go.

Preparing the “Structural Sponge”

The resin can’t just sit in thin air. For that, I used the sponge and the cling film. Draping the cling film over the sponge and then pressing it against the window frame from the inside gives:

• A support structure in the shape of the window we want, 
• Sealing to the back, so I can now hold the wall flat, and the resin won’t just pour out the other side, 
• A nice convex shape that makes the glass slightly pop out of the frame later (if one is lucky…).

Structural sponge assembly

Pouring the resin

Pouring the resin is very easy as it comes in dropper bottles. If you mix the correct colour, it is worth using a silicone cup for that (you can harden the excess in there and then just pop it out).

Filling in the window with resin on top of the structural sponge

As hard as Ceramite: curing the resin

The resin was hardened using the UV torch mentioned above (Darkbeam). I also have the larger UV light, which makes the process a lot easier as it has more power and a much broader beam, however, either is absolutely sufficient. Given the small amount of resin used, it only takes a few seconds to cure. 

Note: it seems that this resin doesn’t go yellow if you “over-cure” it, so there is no reason not to be on the safe side and give it a bit more radiation.

You can observe the curing as the resin has a very slight shrinkage, so any light reflection will abruptly change as it hardens. 

Hardening with UV torch

Disaster strikes - or does it?

Now, there is a drawback in not using proper UV-stabilised and heat-resistant film… cling film can melt. This generally only happens when the resin has nearly fully cured, and the heat has been generated from the process. The cling film will attach to the back of the window and separate from the rest of the film on the sponge, leaving the sponge pretty much clean in 95% of cases.

So, I peeled back the structural sponge and film and looked into a rift in the crucial film layer. Whilst my heart momentarily sank and I cursed into my mask, it was not much of an issue, thanks to the great properties of the resin. Not great, not terrible.

Damaged film and uneven resin window

I bit the bullet and simply applied a layer of resin to the back of the window, completely covering the melted cling film (after curing it more from the back to make sure it was all good to go). The layers of resin do not cause any optical disturbances or artefacts that I would find negative in a stained glass window - in most cases, you can not tell where the layers meet. And thanks to the transparent cling film, even after slight melting, it is not visible once encased in resin from both sides. 

Filling the back of the window and hardening it

If you’d rather not have that issue, move the lamp over the resin from side to side and cure it in “stages” to manage the heat issue. Ideally, you’d want the back to be still quite liquid, so you flip it over and lift off the sponge and film - this generally doesn’t cause the colours to spill/mix if you’re careful. Just make sure to cure the resin on the cling film and sponge before putting it down though. This will also nicely show off the shrinkage as it pulls together the cling film as it hardens.

Another way to avoid such issues is, of course, using resin specifically, UV and heat resistant foil/film. I have some here and will try more, but I find that it is not flexible enough to give that convex shape. It doesn't stretch but “folds”/creases, which is just not a good look.

N.B.: You can mix resin with different colours (acrylics, etc) however, this can impact curing. Epoxy resin pigments might be a viable option - yes, I have already ordered some because of brain squirrels and might update this if it works. Anyways, the issue is that resin that remains “tacky” or “sticky” after long curing will simply not cure. Ever. It will remain like this and will not be “safe to touch” on the gaming table. So please check that the resin is cured properly and mix responsibly.

Tinting/adjusting the colours (optional if you don’t cock up the colours, which I did, so it was mandatory)

I had the unfortunate experience that the resin did not entirely cure in the colours I had imagined/wanted. I was hoping for dark ruby red and a solid amethyst purple… sadly, it was reminiscent of the early Fisher-Price plastics (or V-Tech toys, for the younger readers). The good thing is that you can tint the resin, to an extent, after application. The easiest way of doing so, in my experience, is using candy inks (I used Green Stuff World’s Candy Ink) via an airbrush. These inks are very pigment-intense but have incredible fine pigment structures, so you get a nice “see-through but strong colour” effect. You can use a brush, but you risk leaving brush strokes, which are very hard to avoid on a translucent medium (I tried).

A finished window

“This was rather enjoyable” - things I found easy and I liked about the project

One surprisingly easy thing is to get the resin to level in the window frames, as it is self-levelling in nature. This makes the whole process a lot of fun, as the window panels come together quite quickly and get a nice, smooth finish.

Once I got used to preparing the sponge (you need to use new cling film for each window panel), I quite enjoyed lining things up and figuring out the patterns of colour that I wanted to go for.

“Challenge Accepted” - things that weren't so smooth

Finding the right thickness of foam/sponge was not a long journey but literally a painful one. My first attempt was simply using my gloved finger and the cling film to press under the window frame to seal it. This seemed like a very efficient and smoooort move because I could get exactly the shape I wanted in terms of a convex shape and had perfect control over how well things were sealed. Clever boy. 

The critical failure came when I realised that I had forgotten that the curing is exothermic: once you shine the UV light on the resin, it heats up. Quickly. And a lot. Which is a bad combination to have on your black gloved (I.e. UV heatable) finger… So save yourself the burns and simply use a sponge of about 2cm thickness. (Note: the heat is only of a short duration and is proportionate to the amount of resin you use. It has not in any way interfered with the plastic of my model or the paint on it.)

Tips and tricks

If using a UV torch rather than a larger beam lamp, move the torch about so you cure everything evenly. Otherwise the shrinkage can result in waves and ripples on the surface (and now you also know how to do water effects with resin).

Limitations

The window size is a limiting factor, depending on the size of the sponge and foil you have rigged up. This goes hand in hand with the limitations that come from having an already assembled building, rather than flat singular wall elements.

The cling film is a suboptimal solution but has the next flexibility I found. Any thicker, and you don't get the convex shape, so the window looks way too thick in the frame (and only one side of the frame (the back)). 

“Heed this warning…”

A few things to keep in mind if you'd like to venture down this path.

First and foremost: most resin has some toxicity, which comes in two flavours: VOC (volatile organic compounds, i.e. gass-off) and radiation (UV curing light). Yummy.

The resin cures rock-hard - therefore, you need to ensure that it is where you want it to be before you harden it. Otherwise, sadness will occur.

Bubbles… if you are not very careful, and even if you are, you might get a couple of bubbles. Toothpicks and taking your time to inspect the poured resin THOROUGHLY can help a lot here, though. 

Fun fact - the resin gets hard enough so you can drill into the bubbles once cured and fill them again afterwards. I would, however, say that this is tedious, and milage varies wildly in terms of the end result.

If I knew then what I know now...

As is always the case, I have learned so much doing this project that I now wish I could just go back to the beginning and do it better. Then again that is what the other models in my “pile of potential” are for. Here are the things that I would like to do differently next time.

I would definitely try and mix the correct colours exactly as I want them beforehand and then apply them to save time and effort on the tinting later. A set of resin pigment powders and some silicone mixing cups are about to arrive, so there will be further experimenting. 

Given how hard it was to hold the assembled model (even though the two levels were not connected), I would not assemble the building first but do wall segments instead - like a normal person.

Looking at the tools I used, I would have used a larger sponge and glued it to a piece of board to have a tool that I could simply put the cling film on and then press the wall segment onto from the top. That would have sped up the process and saved me a finger cramp or two.

Regarding the above, I can now do one wall segment worth of windows in about 30 minutes. This could be cut in half by building a holding tool or having a helper to hold the structural sponge in place. 

Something that would have been very easy for me to do with my setup but that I simply blanked on was applying lacquer in advance. Next time, I would probably try applying gloss lacquer to the frames first to ensure the resin flows in easier and does not stick to them after levelling out, leaving “tide marks.” 

I would work with a more limited palette of colours to make sure that it fits with the grim-dark vibe of my painting style and does not clash. (I had to do some tinting to overcome the Fisher-Price/V-Tech effect for this one).

+ + +

Charlie: Thanks Boris! Putting together all this information is time consuming, particularly given all the photos, and doing that extra little bit to demonstrate the technique on. The effort is greatly appreciated, you glorious nutter.