Site Model Failings.
Since a few groups started using plasters and concretes for site models we’ve seen a few re-occurring errors. A cast will only be as good as the form so do take time to experiment with materials, varnishes, lubricants etc. A common problem is that the material used to make the form is too porous, meaning it absorbs the moisture from the plaster. This can lead to it warping and damaging the cast or making it difficult to remove once set. An effective way to tackle this is to varnish the material, but this is not always a fail safe method. Above we used mountboard for the roads and greyboard for the building plots, even though we varnished the former the greyboard still absorbed to much water which made it difficult to remove from the cast, the mountboard however peeled out cleanly without tearing or sticking behind. However a more fail safe method would be to use acrylic for the entire formwork as it is the quickest, cleanest and involves least amount of effort to remove the cast from the former, although you must flip the drawing before laser cutting due to the slight taper that occurs when laser cutting acrylic sheet.