I think I said how hard can it be, this spray painting lark. Well, the answer can be very hard, in fact it's taken me ages to just get things going and following a disaster with the wrong colour backscene blue I'm finally content with the outcome. It's far from perfect but I would be the first to admit that I'm no artist, what you see is just my best efforts following much pawing over YouTube and taking some photos. The trouble is only years of practice in my hands would yield the results I'd imagined and I want to get on with track laying so this will do. Having said that as the landscape comes up to meet the sky their may be some minor modifications but at least I have something that should not detract from the railway, I didn't want unsightly things in the background to spoil the illusion I'm after.

Here is the 3mm ply in place:

And now painted white with a rough idea of the land height taken from the SCARM model:

Preparing the cloud masks:

So here it is, lighting is not all up yet, it looks a bit lighter in real life. Next job is to remove all the masking sheets, have a good clean up.

The 2 clouds on the bottom of the next pic were used for practice and will be covered by hillside later.  

I used Dulux "Blue Babe" for the background, applied with a roller. I then used Vallejo airbrush paint - White & Grey to create the clouds. I made some stencils from art pad paper using a scalpel to help me get the position of the clouds down. The picture below shows the clouds just stencilled on using a white wash before the shading took place with light grey and white.

And some of the many stencils I made:

The airbrush is an Iwata Revolution CR I purchased about 18 years ago with an Iwata mini compressor as a kit, the needle is a little large (0.5) but it seemed to work fine. I don't know a lot about them but the set was about £100 back then if memory serves me right.

A couple more pics to finish: