Ty-Mawr Lime Hemp Plaster

Lime hemp plaster is the preferred choice for finishing boards internally; it is suitable for Schneider Woodfibre Boards, Amorim Expanded Cork Boards and the CEWood Wood Wool Boards.

Made with a non-hydraulic lime, this plaster build up creates a highly vapour permeable finish that helps to mange internal air quality. The highly fibrous nature of the hemp plaster provides a robust finish that does not require a render mesh throughout the plaster, reducing use of plastic and making application easier.

This system can be applied in 2 or 3 coats depending on the finish required, we have a range of options below.

Standard sand lime plasters (hydraulic and non-hydraulic) are not suitable for application to boards due to the weight and granulometry of the plaster.

FOR INTERNAL USE ONLY - when plastering onto boards externally please use the Secil Render System.

Coats and finishes

The hemp plaster is always the base coat onto the boards, but it can be finished with a range of top coat plasters depending on how smooth the internal finish needs to be. A finish coat of the TopLime Hemp provides a fabric like texture similar to traditional plasters and would be often be found in cottages, whilst the TopLime Chalk and TopLime Internal finishes create a smoother more ‘formal’ finish found in many townhouses. Surface finishes are subjective, please contact the sales team to request samples of available finishes before ordering. 

Methods A & B have courser granulometry in the finish plaster requiring a 6mm finish coat, which means only one base coat and one coat is required. Methods C & D use smooth finish plasters with fine granulometry at 3mm thick, which require two base coats of the fine hemp and one top coat.

Method A

A two coat method for a textured finish - provides a traditional cottage feel often used with wet edges corners (no beads). This finish is a favorite with our customers in a wide range of applications.

1. 6mm TopLime Hemp Plaster
2. Jute Scim reinforcement over areas of high risk (see application advice)
3. 6mm TopLime Hemp Plaster

Method B

A two coat method similar to method A - which provides a smoother finish whilst maintaining the fabric-like texture. This finish is used where the finish should have some character, but the hemp texture is a little too pronounced.

1. 6mm TopLime Hemp Plaster
2. Jute Scim reinforcement over areas of high risk (see application advice)
3. 6mm blended hemp finish (50/50) - see below

The blended hemp finish (also called 50/50) is achieved by mixing the TopLime Hemp plaster with a smooth finish plaster such as Toplime Chalk or the Toplime Internal (previously superfine). This allows the products to be mixed at varying ratios to reduce the texture of the hemp plaster, typically this is mixed with one bag of each plaster (50% of each, hence the 50/50 name). A blended finish is chosen when the smooth finish plasters are not required but the texture of hemp alone is too pronounced.

Method C

A three coat method to achieve a smooth finish, the Toplime Internal finish is a common choice in townhouses and Victorian properties.

1. 6mm TopLime Hemp Plaster
2. Jute Scim reinforcement over areas of high risk (see application advice)
3. 6mm TopLime Hemp Plaster
4. 3mm TopLime Internal Plaster

Method D

A three coat method to achieve an extra smooth finish, the Toplime Chalk finish uses a chalk aggregate giving it a tighter finish than finsh plasters made with fine sands.

1. 6mm TopLime Hemp Plaster
2. Jute Scim reinforcement over areas of high risk (see application advice)
3. 6mm TopLime Hemp Plaster
4. 3mm TopLime Chalk Plaster

The Toplime Chalk plaster includes fine hemp fibres (different to the hemp shiv used in TopLime Hemp) which reinforce the top coat.

Applying Jute Scrim

• Apply a thin coat of hemp plaster approximately 200mm wide over the area to be reinforced
• Trowel lengths of jute scrim into the plaster ensuring the scrim is well embedded
• Apply 5-6mm hemp plaster to infill the sections between, and to cover the jute scrim
• Trowel the entire wall to achieve a consistent thickness
• Key surface with an even and open texture.

Wait for 7-10 days between coats to allow plaster to pull in until knuckle hard (too firm to dent with a knuckle but still soft enough to scratch with a fingernail, retaining some moisture). Drying times will vary depending on conditions, so monitoring of the plaster and site conditions is essential.

For a final finish of fine lime hemp or a blended hemp finish, no additional basecoat is required. The base coat of fine lime hemp should be left with an even open texture but does not require a heavy scratch used on a conventional sand lime plaster.

For a finish of Toplime Chalk or Toplime Internal finish, a second base coat of 6mm fine hemp is required. The first coat should be allowed to cure for 5-7 days until knuckle hard before applying the second base coat. The second base coat should be allowed to pull in for 2-3 days before floating the surface with a poly or wooden float to flatten the surface. A light key can then be applied to the plaster using a stiff bristle brush, this should not be too deep as it can show through the finish plaster. Do not use a devil float on the hemp plaster as this will pull fibres out of the surface.

Benefits of Lime Hemp Plaster 

• Highly vapour permeable
• Well fibred plaster which provides a strong robust finish
• Variety of surface finishes available
• Two coat system for simplified installation (Option A and option B)
• Suitable for Limewash or breathable paint finishes