Ironstone Pre Mixed Lime Plaster
Our range of Natural Hydraulic Lime Plasters are manufactured with the NHL 2 binder from Heidelberg Materials Socli and blended with kiln dried sands. They are combined with carefully selected additives to improve the plasters physical and mechanical properties (with the option of alkaline resistant fibres), whilst maintaining all the virtues of a pure Natural Hydraulic Lime render.
Usage
For use internally in building conservation where the binder strength is appropriate for the host background / surface.
Advantages
- Quality controlled production
- Features the feel of a modern render
- Significantly improved workability and reduced risk of shrinkage
- Slower drying; better curing
- Salt resistant
Ironstone Basecoat Plaster is suitable for coarse plaster coats typically known as scratch and float coats. The addition of the fibres provides reinforcement and improved tensile strength of the scratch coat and assists to mitigate cracking, on high suction backgrounds.
Ironstone Finishing Plaster and Superfine Finishing Plaster are both suitable for finishing plaster coats. Do not use these products below 5 degrees or if freezing conditions are predicted over the following few weeks. Do not use this product in temperatures above 30 degrees.
Coverage
After mixing, a 25kg bag will produce approximately 15 litres of mortar.
Ironstone Basecoat Plaster - A single 25kg bag will cover 1.5m2 at 10mm thickness onto a flat wall.
Ironstone Finishing Plaster - A single 25kg bag will cover 5m2 at 3mm thickness onto a flat wall.
Ironstone Superfine Finishing Plaster - A single 20kg bag will cover 5.6m2 at 2.5mm thickness onto a flat wall.
Colours
These products are entirely natural.
Ironstone Basecoat Plaster - made with an off-white sand which results in an off-white plaster when floated.
Ironstone Finishing Plaster - made with a fine brown sand which gives a light brown plaster when floated.
This plaster gives a lightly textured finish when floated with a plastic or wooden float, the finish is quite smooth when sponged but still moderately textured.
Ironstone Superfine Finishing Plaster - made with a light cream silica sand and crushed limestone, this gives a nearly pure white finish when trowelled or an off-white when sponged.
Surface Preparation
Dense impervious backgrounds will require little to no dampening, whereas very porous backgrounds will require adequate dampening to prevent rapid drying. Ensure surfaces are clean and free of dust and other debris.
How to Mix
A 25kg bag of Ironstone Basecoat Plaster will require 4 to 4.5 litres of clean water. A 25kg bag of Ironstone Finishing Plaster will require 4.6 to 5.4 litres of clean water. A 20kg bag of mortar will require 6 to 9 litres of clean water. Always avoid making the mix too wet, as this can promote shrinkage issues.
Ironstone Basecoat Plaster and Ironstone Finishing Plaster - First add around 60-70% of the water followed by the Ironstone Basecoat Render / Finishing Render and mix until the water is fully distributed, then add additional water to the desired consistency. Mix for 5 – 10 minutes. Ironstone Superfine Plaster - First add around 80-90% of the water followed by the Ironstone Superfine Finishing Plaster and mix until the water is fully distributed, then add additional water to the desired consistency. Mix for 5 minutes. Whisk mixers are also suitable for use. Like most lime renders and plasters this blend will benefit from quenching. Allow the mix to stand for 10 to 20 minutes after mixing before use. Ironstone Plasters may be re-worked for up to 14hrs.
Ironstone Basecoat Plaster
Our Ironstone Basecoat Plaster will be suitable for use onto masonry backgrounds with some suction. For application on to very smooth or highly porous backgrounds then a coat of Ironstone Bonding Coat should be applied first.
Wood wool render carrying boards like Celenit are also suitable substrates. When applying to render carrying boards the suction from the board should be adequately controlled before application. Apply two coats, the first coat should be applied in a ‘two pass, one coat’ system.
Applying the first pass at 5mm then embed 4mm render mesh with a trowel then immediately recoat to give a total thickness of around 7mm. Apply a scratch coat without pulling through the mesh. Damp cure and protect for 7 days before applying a second coat at a target thickness of 5mm, finishing by float and optional sponging. On all backgrounds Ironstone Basecoat Plaster should be used as a minimum two coat system as a single coat application will ghost through the background.
How to Apply
Always wet a substrate, including previous render layers, to control suction before use. However, you don’t want to be laying onto water sitting on the surface as this will act as a slip layer. Dub out the wall to bring it roughly flat by filling pockets, voids or missing pointing with a relatively stiff mix. After dubbing out a shallow scratch coat should be applied to areas filled. Allow 48hrs for this to stiffen sufficiently to take the scratch coat. Keep these areas damp by misting until scratch coat is applied.
The scratch coat should be applied at a target thickness of 10-12mm, this should be scratched using a crosshatch pattern scratch to approximately 1/3 of the depth of the render. The more common wavy line scratch used on cement renders is not suitable for this type of material. This coat should be left for 7 days to build up strength to take the float coat. During this time the render should be damp cured by mist spraying, and protected from direct sunlight / drying winds, preferably with damp hessian.
The float coat should be applied at a target thickness of 8-10mm and should not be thicker than the scratch coat. This should be floated with a wooden or plastic float to compress the surface; lime renders should be stiffer than cement renders at time of floating and shouldn’t drag under the float. Optionally this can be sponged up after it’s stiffened to give a smoother surface of this is to be the topcoat. If the Ironstone Finishing Plaster is to be applied, then this coat should be devil floated to give a light key and allowed to cure for 5-7 days. During this time the render should be damp cured by mist spraying and protected from direct sunlight.
Ironstone Finishing Plaster
Our Ironstone Finishing Plaster is a topcoat plaster for application on Ironstone Basecoat Plaster, Cornerstone Insulating Plaster, Wood wool render carrying boards like Celenit. or sound old lime plaster.
How to Apply
Always wet a substrate, including previous plaster layers, to control suction before use. However, you
don’t want to be laying onto water sitting on the surface as this will act as a slip layer. When applying over Ironstone Basecoat plaster apply at a target thickness of 4-5mm and finish by floating plus optional sponging.
When applying to Cornerstone insulating plaster apply at a target thickness of 4-5mm and finish by
floating plus optional sponging.
When applying to render carrying Wood wool boards. Apply following ‘one coat, two passes’ of Ironstone Basecoat plaster. Waiting 7 days before applying the finishing coat at a target thickness of 3-5mm, finishing by float and optional sponging. When applying over old sound lime plaster use the Ironstone mineral primer first before applying at a target thickness of 3-5mm and finish by floating plus optional sponging. After application the plaster should be kept damp to promote the cure by mist spraying, and protected from direct sunlight / drying winds.
Ironstone Superfine Finishing Plaster
Our Ironstone Superfine Finishing Plaster is a fine topcoat plaster for application on Ironstone Basecoat Plaster, Ironstone Finishing Plaster, Cornerstone Insulating Plaster or sound old lime plaster.
How to Apply
Always wet a substrate, including previous plaster layers, to control suction before use. However, you don’t want to be laying onto water sitting on the surface as this will act as a slip layer. When applying over Ironstone Basecoat plaster, Ironstone Finishing plaster, Cornerstone Insulating plaster then apply the first pass at a thickness of 1mm, let this pull in and stiffen before going over with a second pass at 1mm. The overall target thickness should be 2mm, and a maximum of 3mm. Finish by floating plus optional sponging.
When applying over old sound lime plaster use the Ironstone Mineral Primer first before applying the first pass at a thickness of 1mm, let this pull in and stiffen before going over with a second pass at 1mm. The overall target thickness should be 2mm, and a maximum of 3mm. Finish by floating plus optional sponging. After application the plaster should be kept damp to promote the cure by mist spraying and protected from direct sunlight / drying winds.