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Scratch Building Techniques

DocRef: JC22a

Scenic Structures from Scratch

If you are wanting to represent a particular railway at a specific period in time, then scratch building is the only option.

The choice of materials for doing this will depend on whether or not the models are required to be weatherproof.

The basic materials which can be used are timber, e.g. plywood or MDF, plastic card either plain sheet which your score yourself to represent a particular surface or selected from a limited choice of embossed plastic card, or resin, polyurethane gives the better results when compared with polyester types.

Any of these materials can be used outdoors but will require a measure of protection. The sheet timber options, plywood, MDF, will require treatment against moisture, otherwise decomposition will soon occur, while the plastic options, polystyrene, ABS, etc. need protection against UV, otherwise they go brittle and crack. Resin is generally the best option, since it highly resistant to everything the "elements" can throw at it but is the most complex process and can be costly.

There is one further option for garden structures and that is concrete : This can produce strong structures such as bridges and platforms but will require moulds for casting, as does resin and is prone to frost damage.

If using timber to represent brickwork, you have the option of laser cutting : While this is a convenient method, I find that the resulting brickwork lacks "texture" and everything looks too "regular". Real brickwork is never that perfect in symmetry, etc. (some will say I am too "fussy")!

A few words on types of "bonding" in brickwork is appropriate at this point : Until the advent of "cavity walls" in the latter half of 20th Century, most British buildings were constructed of two basic patterns of brickwork, (ignoring the "frippery" of mock-Tudor and other ornamentation), these were "English bond" and "Flemish bond".

Put simply, English bond is produced by alternate horizontal rows of "headers" and "stretchers". A header is a brick displaying its end profile and a stretcher displays its length. Such bond is two bricks in thickness, the "headers" bonding the two layers.

Flemish bond consists of alternate headers and stretchers in each horizontal row, alternate rows being arranged so that the mortar joints are staggered between those of adjacent rows, again the wall is two bricks in thickness, the "headers" providing the bonding.

Cavity walling as is seen in all modern house building usually consists solely of stretchers, unless decorative "frippery" is involved. This permits the cavity, the moisture barrier, between the two skins of brickwork, the two skins being bonded by metal "ties" set in the mortar joints.

Brick-built railway buildings dating before the 1950s would have been of English or Flemish bond. As an example, the GWR built signal boxes which were of either type of bond.

Here is an example of the use of resin casting to produce convincing brickwork

Below is a section of brickwork,English bond type, cast in resin and it has texture, which makes it look "aged" and "weathered". I will describe the processes I used to produce this in more detail below.

The sample shown was produced by making a pattern from miniature (G-scale) terracotta bricks. The full bricks were cut to produce headers (half bricks in this case) and the courses were laid out and glued to a thick, plastic card, base. The bricks were "pointed" using model filler and a mould was made from silicone rubber. The mould was used to cast sections from polyurethane resin, those sections being glued together to form larger wall sections. Acrylic paint in varying shades of blue, grey and red/brown were applied, using both a "dry brushing" technique and a thinned "wash" to "tone down" the colours.

You will find more details of making patterns and moulds here

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Page last modified on February 28, 2018, at 10:53 PM