MDF Concrete

A few months ago a modelling friend wrote to me in a response to one of my posts about the station building I wrote about on this blog. He said that he was intrigued by my use of 6mm plywood for the box that formed the inner shell of the model. I cut the ply parts to size, glued them together and smeared them with DAS modelling clay which I retained with a bit of white PVA. I think what he was questioning was why I would use such a thick, heavy material to build a model when there were plenty of thinner, lighter building materials available. I have to admit that this same question has crossed my mind so I thought I might cover some of my reasons for using such a thick and robust (I prefer this to heavy) material to construct my models. This is especailly relevant when you consider that up to beginning work on the station building I had used styrene and stripwood exclusively to construct my models. .

Perhaps the first thing I should say in relation using thick, hardware grade materials such as 6mm plywood and MDF for the basis of models is that the main reason I decided to go this way in the station building was because of my use a new modelling material: I had never used DAS modelling clay before. In planning the structure I knew I wanted to gain the depth a thicker material would provide for the inset doors and windows that were a feature of the building, but I was also worried how a thin material would take to being covered in a 2mm thick layer of air drying clay. I was concerned that a thin material (I’d used 1.5mm sheet styrene for most of my modelling up to this point) would warp. In the past some of my styrene buildings had warped all on their own without having to cope with a layer of DAS and I wasn’t sure I could get the clay to adhere to a styrene substrate anyway. A friend once accused me of being a belts and braces type of person: I guess he was right because I decided to use 6mm material for the station and I’ve gone with even thicker material on the bridge I’m currently building. Did I overcome the warping problem I was worried about? I have learnt over the years that the thickness of a material is no guarantee that it won’t warp: the secret to preventing a building material moving in a direction you don’t want it to is to understand the material and work with it. No amount of force and bracing will prevent warping if the circumstances are right. So my answer is: come back and ask me the same question in ten years and I may have an answer for you.

A second important point to note is that the structures I’ve been building lately represent masonry and concrete. If I were trying to represent a wooden building I would not have used such thick material but would have chosen scale thickness wood. What I’m essentially replacing in the building of these structures is the use of styrene brick sheet with a layer of the DAS clay, which does a far superior job of representing “stone” structures than plastic in my opinion. This is not really surprising when one considers that DAS is a mix of clay and chopped paper, so its basic composition is much closer to the material it is being used to represent. It is far more labor intensive than using plastic brick sheet, as one is essentially required to carve a representation of the stonework into the surface of the dried clay, however it produces a final texture that simply can’t be matched by the use of plastic. Well that’s my opinion, other may disagree.

One of the upsides of using the thick substrate material such as 6mm play and MDF which can be sourced from a hardware store is that it is far cheaper than using “modelling” materials. I go to my local Bunnings and buy a small panel of good quality ply and I have sufficient material to build 5 structures. Traditional modelling materials are almost always much more expensive. Another advantage for me in using these materials is that I have the tools available to work it into the shapes I want: I admit that not everyone has the same tools available to them that I have but the one advantage to buying yourself a couple of good power tools is that they can be used for all sorts jobs, not just exclusively for modelling. Tell the missus that you want to buy a good quality mitre saw so you can knock up those planter boxes she’s been nagging you about making. I’ll leave the rest up to you 🙂

The bridge I’ve been building over the last couple of weeks had reached a stage where it was ready to position on the layout. I had some photos of a similar bridge I had taken a couple of years ago on the Murwillumbah branch line about 2 km from my home. I used these as a guide for the bridge piers and abutments that I needed to make to allow the installation to proceed. I decide to use a range of different thickness MDF to form the substrate of these: I placed the bridge in position, did some measuring and cut and chopped various bits about till I got roughly what I was after. The piers and abutments I’m trying to represent are poured concrete that has a series of cast lines in their surface which looks to have been the result of wooden planks used as the form work for the concrete pour. In spite of my expectation that these lines would be proud of the surface of the main structure the photos appear to show that the lines are convex in shape, similar to mortar lines in brickwork. My plan is to coat the basic MDF formers with DAS, sand these semi-smooth and then scribe the lines into the resulting surface, after which I will colour the surface to represent the streaks and stains I can see in the photo.

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