Model Engine Works: December 2020

An important part of displaying and photographing my models is the Diorama backdrops they are shown on. I have found that something with a raised track on an embankment or over a small bridge is useful as it allows for eye level shots.

They do not need to be large and are also a good way to display items of stock at home or at shows, a very good way of practising scenic techniques without committing to a full layout. They can be formed from any light and rigid material such as polystyrene or Polyboard. For my recent ones, I have been using 25 mm polystyrene bonded between outer skins of 4 mm plywood. This gives an extremely light and rigid block which may be shaped with a sharp blade. A sharp short pointed kitchen knife if you are allowed one of these.

I have left the base plywood as a rectangular piece and the upper skin has been pre-cut to the shape of the track bead, this makes it much easier to work the profiles of the surrounding landscape into the polystyrene core block.

I usually, work from a plan sketched on a piece of wallpaper lining paper; this gives me the position and scale of the main elements of the scene, roads, rivers, rocks, structures, walls, fences, gates and trees. For my latest scene, I have used a small stone bridge, the kind that would be used on an embankment to allow for a small lane or river. This has given me an excuse to add a kink in the track plan, always more interesting than a straight piece of line.

After cutting out and gluing the plywood and polystyrene together with PVA the glue they were cramped together using a workmate vice, it is best to leave this overnight as the PVA takes some time to dry between the polystyrene.

While this is drying the stone bridge was formed so the landscape could be carved out around it and make sure we get a snug fit. Other elements like fencing and trees can also be pre-made at this time. For this scene, I have used a combination of stone walls, wire fence, and hedges.

The bridge and parapets have been formed in Wills embossed plastic sheet random stone with corbel sheet forming the coping's, the bridge was made in two halves so it could be glued back together again under the trackbed when fully painted and weathered. A base coat of a dark buff colour was used, then further thinned and dry brushed coats of grey, charcoal and earth brown were added, further thinned and dry brushed coats of grey and olive green finished the paintwork off. This should not look uniform but also be in the right areas. The dark charcoal staining on the upper parts of the stones, the green staining around the base and some run down from the coping’s, some areas of buff should still show through the other thin layers of paint.

When the base has dried, I used a sharp short pointed kitchen knife to carve the polystyrene to shape following the profile of the plywood trackbed as a guide. I then used the pre-made bridge to gauge the hole needed under the track for it to fit correctly with the capping’s level with the top of the track.

A rasp file was then used to take all of the sharp edges of the plywood and blend it in with the polystyrene. The edges of the block were then smoothed with some 240 grid sandpaper.

The next stage was to give the whole diorama a durable shell to apply the decorative finishes too. I have used a brown gum paper tape; this is available form art materials suppliers. I use this for lots of cold moulds forming in my projects, and by building up multiple crossed layers on a former, it is very strong and durable when dried. I used about 6 layers on this diorama, formed in two stages, letting each application of about 3 layers dry before applying the next. Ones it dries it contracts and tightens on the mould.

Next I added the track, Using Peco 009 rustic flexible track formed into the shape I required, this was bonded to the upper plywood surface with PVA glue and held in place with small clamps overnight till the glue dried. Once dried a couple of check rails were added to the curved sections each side of the bridge, these also extending over the bridge and were held in place with some track pins. The sleepers were predrilled before these pines were pushed in place with some pliers. It was necessary to bend the check rails to shape before fitting them. I painted the sides of the rails with a dark grey & brown mix of revel oil paints to take the shine off the new track work.

The bridge could now be fitted in place ready for the landscape base material to be added around it. The two halves were bonded together with polystyrene cement and then glued in the correct position on the diorama using some contact adhesive.

For the landscape base I used a mix of plaster filler, PVA glue, and mixed brown powder paint into the mix. This gives a pre-coloured base paste which does save painting the landscape before applying scenic materials such as static grass and scatter materials. It also has the advantage of a stronger plaster that can be applied in a thinner layer which is there for lighter, and if you work it after you have finished the scenery it does not show white through, just a soil colour. The more PVA you add the smoother the mixes surface will become and the longer it takes to dry. Add as little water as possible to form a thick paste, as a dryer mix is easier to apply.

After letting the base landscape mix dry my thoughts turned to add the track ballast. I wanted a fine stone for this and came up with fine dry building sand which has been sieved. I then added some grey powder paint to this and mixed it dry. Because of the colour of the sand, this did give me a darker coloured ballast, this was not a problem as I wanted to dry brush a lighter grey over some areas and other parts will be covered with static grass. The powder was added round and between the track dry and a medium sized paintbrush used to spread the ballast in and around the sleepers. This was then fixed with a glue mix off 50% PVA and 50% water; a small drop of liquid soap (washing up liquid) is also added to allow the glue to flow through the powder. The glue mix was applied with a syringe; two lots of glue were applied, leaving the first to dry overnight.

The landscape materials were a mix of 3mm late summer dry grass and 2 and 3mm mid tones of green static grass, I used some sponge scatter in patches to give depth to the landscape colour. A rock outcrop and banking was formed using some small sandstone shards crushed up into 4mm scale rocks and bedded in the plaster before it set.

Trees were formed with wire armatures which I painted with a plaster mix similar to the landscape. A mixture of landscape material ware used to form the foliage, these included Woodland Scenics foliage and sponge scatter added to the armatures with contact adhesive and PVA glue. Some small trees ware formed with a bamboo trunk and lichen sprinkled with sponge scatter applied over the top. This method was also used to form gorse bushes with the yellow flowers being added by using a yellow acrylic paint dabbed over the top and upper sides of the bush.

For the fencing I used lollypop sticks cut to a suitable section and length and drill with some fine holes through which I threaded a grey cotton thread, leaving this long to allow the fitting of the fence posts before drawing the thread tight and sealing it with PVA glue.

Tuesday, 8 December 2020

4mm-3mm Scale Photographic Diorama