How do I make windows look opaque?

[ColinK]

I am making a low relief factory building in G scale using a much modified Piko kit. It has 8 large windows in the roof, I think northlight is the technical term. The kit windows are made from clear hard plastic and are about 2” x 1”.

 

There is only 1” behind the ‘glass’ to the rear of the low relief building. Hence I need a way to stop people seeing through the glass. I hoping readers can offer some solutions.

 

Methods I found on here include putting greaseproof paper behind the windows, painting with a thin ‘dirt’ wash and using fine sandpaper to make them look opaque.

 

It would also help if I can reduce the shiny look on the outside of the window. Would matt varnish or Testor’s Dullcote work?

 

Thanks.

[Bristol_Rich]

In the past I’ve used very very fine wet and dry paper (dry) rubbed against the rear surface in very small circular motions, rotating the piece through 90degrees as you go.

 

It’s a lot easier if you cut a piece of the glazing material larger than you need, work it and then cut the sized section out of this. It prevents you focusing your efforts in spots and provides a more uniform finish.

 

If you varnish the glazing there is a risk it will go foggy/opaque but will be inconsistent and look a bit messy.

Edited September 26, 2018 by rich_eason

[KalKat]

You could also try solvent -  produces the effect of ripple/hammered glass

 

 

Emma

[F-UnitMad]

Dullcote will produce the opaque effect by itself. I sprayed the back of these windows (clear plastic) with a light spray of it & this was the result.

 

[Mick Bonwick]

Another fan of Dullcote here - it will work straight away on just the outside of your windows. Task complete in seconds!

[JeffP]

Solvent does the trick.

[E3109]

This stuff works a treat. Wilko's had it on offer a bit back, but seems it's back to full RRP there now.

 

https://www.wilko.com/en-uk/rust-oleum-frosted-glass-spray-paint-400ml/p/0413351?nst=0&gclid=EAIaIQobChMI0L2n_ajZ3QIVjp3tCh2aqwo3EAQYASABEgKk0PD_BwE&gclsrc=aw.ds

[Irish_R_M]

Cheapo reversible options here - magic tape in any good stationary shop, comes in a 1" roll. Apply to the reverse, job done. Alternative is laminating pouches which come in A5 sizes, handy for bigger areas, but has no "sticky" properties. A quick blast of spray mount/glue should suffice. Tracing paper also works.

 

One other one I recall using some years ago, was laminating several sheets of household clingfilm together by judicious use of the rolling pin. Lets more light through than the other options, yet completely obscures the actual internal contents. I used to make up clear corrugated panels for industrial roofs years ago by pressing it between a former. Looks like fibre glass too! A skim of PVA or similar between the sheets, let set for 24 hours, and you have a lifetime supply!

 

HTH, Rich. 

[holywell junction]

Use the opaque plastic from takeaway containers. I used it for a frosted toilet window on a platform waiting room. Looks great. It was fixed with plastic weld.

[newbryford]

Various grades of opaqueness of "sticky back plastic" are available from the likes of ebay.

 

Search "self adhesive opaque" on a well known auction site.

Edited September 29, 2018 by newbryford

[The Johnster]

I think there is another issue here; if you are going to make these 'back' northlights opaque then you need a reason to have the others clear, which I assume you want to do to show interior detail in the factory.  If not, then it's simple, you make them all equally opaque or dirty.

 

Dullcote is probably as good as anything for this in my view.  You might make the point by having a cleaning team up there with crawling boards so that some are clean; they could be working from front to back, but not everyone likes this sort of cameo.  Or you could paint them matt black on the inside if your period is post 1939; many such windows were blacked out as part of the wartime regulations, especially those working night shifts, and these sort of windows, high up and not conveniently accessed, were left in that state for many years after the war ended; you're probably ok up to the 80s in some cases.  A bit of weathering on the outside would give the correct amount of reflectiveness.

[richard i]

Rather than making them opaque make them dirty. They would be fitted for light, why on the roof would you go to the extra expense of being opaque? So no one can look in?

More logical to be dirty.

[bike2steam]

I just give a quick blow over with matt varnish.

[ColinK]

Hi everyone,

 

Here is the low relief building with the top row of windows made opaque by a quick spray of Testor’s Dullcote.

 

 

I sprayed the back of the windows before fitting them in place. As they were slightly bowed I had to stand weights on them while the glue dried. This resulted in the small patches where the weights rubbed the dullcote off. In daylight looks as if the windows are dirty, but with clean patches where the dullcote rubbed off, I think it adds to the effect.

 

The building will have a back panel added in due course.