ModRoc Plaster of Paris Bandage for Modelling



ModRoc Plaster of Paris Bandage

Modroc (or Modrock ) is plaster bandage that is used for modelling, casting and crafting.  So how did it come about that a medical product began to be used in this way?  Many years ago, somebody in the theatrical trade had an urgent problem. He had to make some simulated rocks for a set quickly. He had a brain wave (or, perhaps in the past he had broken a leg and had it plastered with plaster bandage).

The upshot was that he got hold of some plaster of paris bandage, made an armature (rough shape onto which to model) out of chicken wire andmodelled the Plaster bandage onto it. When it had dried sufficiently, he painted his simulated plaster rocks and the set was ready for the production.

So that is how Modelling Rock was first used and over time the rather long name: Plaster of Paris Modelling Rock was shortened to Mod Roc or Modroc (or sometimes spelt modrock or mod rock ) and is still used in ModRoc landscaping.


face casting castCraftmill Modroc  or modelling bandage has a huge range of uses in the modelling world and this is aside from its original use for mending bones. Plaster impregnated gause is used for making a negative pregnant belly casting mask and other body parts. It is used for holding the shape of alginate moulds for a breast mould or  face mould. Modroc is perfect for Breast moulding and face moulding which could not be done effectively without the plaster of paris bandage to fix its shape. Full torso body casting also requires quantities of ModRoc to encase the alginate mould. After securing the mould, you can then make a breast casting and face casting.

Outside of use in body part moulding and casting, ModRoc landscaping is popular amongst model train enthusiasts. ModRoc is a great material for use in creating 3d ModRoc art works. We recommend using pva in the water mix to strengthen the structure and to make it more receptive to paint. As a medium for Sculptors, modroc plaster of paris bandage is extremely versatile. It can be used for creating full size 3D models of large objects when used in conjunction with an armature. Plus many more uses you can think of!

A few tips on using Craftmill ModRoc Plaster of Paris Bandage

Setting Out Your Work

Before you bring water anywhere near your ModRoc plaster of paris bandage, set out the artwork or model carefully. Preparation is most important if you want to ensure that you make the best use of your ModRoc. Remember that once the ModRoc is wet it takes a few minutes before it starts to harden and then for a few more minutes you can mould and work it before it gets too hard. So, speed of working is important which is why you have to think out what work you want to do before you start wetting your plaster of paris bandage.


This is equally important. Take out of your container, or if sealed individually open only what you need. Keep the rest sealed in an airtight container and store in a dry cool place.  Any contamination with water makes it un-useable later. With careful storage, the shelf life can extend to years.

How Much to Soak

If you are making a large, hungry model, which is easy to layer with quantities of plaster bandage, you might be able to soak a roll at a time if it is a small one like for example the12cm or 10cm x 2m rolls.  A large roll like the 15cm x 2.7m roll will have to be slit or cut into lengths to suit the shape you are working on.  Each cut length can be folded zig-zag or rolled up (we prefer zig-zag because it unfolds easier when wet). Small or fiddly models necessitate cutting up short lengths to soak and work with, bearing in mind the workable time of the ModRoc.


The process of soaking and modelling is best done by hand. It is a tactile process. If you use gloves, however thin,  you lose contact with your work. As far as we know, Plaster of Paris bandage is non allergic and it is easy to wash off when you have finished work.  Soak the roll in tepid water (the warmer it is the quicker it sets) for about 5 seconds until it is saturated or the bubbles stop rising (trial and error).


Gently squeeze out excess water or let it run off for a few seconds. Squeeze it too much and you squeeze out the plaster of paris so it won’t set.

Wrapping and Layering

Immediately after squeezing, gently wrap or drape the bandage over and around the frame or object, layer upon layer. Don’t wrap it tightly.


Shape the bandage by hand continuously during wrapping in order to make the bandage adhere and to remove bubbles and cavities. When it begins to harden the shaping process should stop.


The normal setting time is 2-5 minutes but can be changed slightly in the following way.  To accelerate setting, use warmer water or after layering, a hair dryer or heater. You can retard setting by around 4 minutes by using cooler water and by adding 2mg sodium sulfite (anhydrous) per 1000ml of water before soaking.

Preparation for Painting

If you intend painting your work we have some important tips for you.

  1. The surface of ModRoc is normally crumbly so paint will easily pick or rub off even after it dries. Our solution is before soaking the bandage, mix about 1 part of PVA glue to 3 parts of water for soaking.  This has 3 effects, one is (if you want it to) it sticks much more firmly to the base material of your model. The second major benifit is the PVA bonds the Plaster of Paris much more tightly together so paint will not flake off as easily when dry. It does not retard the drying of the PoP bandage. And not least, the PVA glue strengthens the model and helps it to resist water ingress.
  2. Prepare the ModRoc for painting as you would a canvas. We use Leyland Acrylic Primer Undercoat. This can be used for both oil and acrylic paint.
  3. Use good artist quality paints. Now you can buy Fine Artist and hobby Acrylic Paints from Craftmill. We have top quality Acrylic craft paints and also Artist quality high pigment loading artist paints
  4. For protection, varnish the finished work with the appropriate varnish.  You can buy Acrylic Varnishes from our internet shop Caftmill. We stock Acrylic Varnish in sizes from 50ml to 300ml in dead flatt, satin and gloss. We hope these tips prove to be helpful.

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