Archive for April 2013

Plaster Techniques Workshop


On Tuesday 2nd of April a group of clients from across BHT took part in a Heritage Plaster Techniques workshop at First Base.

They started the day by making use of the beautiful plaster work in our building they decided to use the plaster work as models using latex and tissue to build up a mould. They applied several layers of latex by dabbing it on with a tissue and once they built up several layers of latex they began to apply strips of tissue to build up layers. They had to ensure that the latex was well applied into all the crevices on the plaster units to guarantee that the mould would be a realistic replica of the model. They discussed how this technique would be used to restore small to medium sized plaster work during conservation and heritage work.

They talked about how some elements of plaster repair work at First Base were removed from the cornice so that they can used to create moulds and replicated so the cornice can be restored. Discussion was had about the different materials that can be used for making moulds e.g. latex and silicone,  the relative costs and benefits of each and how many times each mould can then be used for.


They discussed how dado rails can be replicated or created using moulds. They took a piece of wooden dado rail each and coated it very thoroughly in Vaseline taking good care not to get too much Vaseline in the grooves of the wood otherwise this would affect the shape of the mould. They also greased a wooden box that was pre-prepared using Plastercine to plug all the gaps.  They then filled the box up with Plaster that they mixed up and left it to dry. Later when the plaster had dried they removed the wooden dado rail moulds and were left with a plaster mould. They then coated the plaster mould with Vaseline again taking care not to get excess Vaseline in the grooves which would affect the shape. They then filled the mould with plaster and left it to dry. When the plaster was dry they removed the replicated plaster dado from the mould. Throughout this process they discussed how the method would usually be used for replicating dado rails up to two metres long. They also discussed how many mass produced dado rails are made using the silicone method they used earlier and how they are made on a large scale production.

They discussed how Modroc plaster bandages are often used to make moulds of statues, gargoyles and sometimes other 3D objects. Sean was volunteered to be the first person to be wrapped in Modroc and Richard (teacher) demonstrated the technique using his face. He covered Sean’s face with the Modroc, building up the layers gradually and smoothing them using a small amount of water. The plaster dries incredibly quickly and the mask was removed after about five minutes. Richard showed everyone how important it was to leave an appendage so that later you can tell how dry the plaster has become. Everyone had a go using someone else as a model. Once the masks had dried used them as moulds and poured plaster into them to create a 3D model.

Last but not least, the group then experimented with aging plaster using glazes and paints using pre-made decorative plaster units. They used a glaze to coat the plaster units and then played around with different amounts and colours of acrylic paint. They used brushes, cloths and sponges to add and remove paint and glaze to highlight crevices. They discussed when this would be used in a heritage context to blend replacement plaster work with the old when carrying out restoration work.