Coverage:
- 120m2 per tonne at 3mm thick
- 3m2 per 25Kg at 3mm thick
Can I use finish plaster for all three coats?
No, the base coats require a coarser aggregate and should be well haired. The finish plaster has a finer aggregate and no hair specifically for finishing lime work.
What is the best way to apply lime plaster?
This advice applies to both hydraulic and putty limes. Although we recommend that putty limes are generally best for internal work. It is extremely important that application guides for the different products should be followed but in general internal lime plaster should be applied as 3 coats:
1st coat: Scratch Coat. Use well graded sands and plenty of hair. Coat should be 6 – 9mm and diamond scratched.
2nd coat: Float Coat. Use well graded sands and plenty of hair. Coat should be 6 – 9mm and floated off.
3rd coat: Finish Coat. Use fine sand and apply 2 tight coats of around 1.5mm.
For other applications and different substrates, please see the application guides in the Documentation section. Substrate preparation, mixing, all procedures - scratching, floating etc and tending must be done correctly and at the right times!
How many days should I leave between scratch, float and finish coats?
Ideally 2 weeks should be left between scratch and float coats, and 1 week between float and finish. The minimum is 5 days. But, every site and every application will be different, expereince is crucial - it needs to be monitored daily as it is ready for its next coat when you can push a fingernail in but not a knuckle - call for advice if you are unsure!
Can I use lime plaster on ordinary qypsum plasterboard?
No, conventional plasterboard does not have a coarse enough surface to provide a good key for lime plaster. Also it is normally necessary to wet the substrate to minimise suction prior to lime plastering. Plasterboard does not react well to being heavily wetted. We suggest using 15mm Ty Mawr wood wool board as a background carrier for lime plaster.
How do I fix wood wool boards?
Wood wool boards can easily be cut to shape using an ordinary site saw. The number of fixings and spacing of battens to support the boards will depend on the thickness of board to be used. Information on this can be supplied on request. Boards can be fixed using ordinary sheradised or nickel plated screws the length of which should be the thickness of the board plus a minimum of 25mm. For external application or where screwing into green oak, it may be advisable to use stainless steel screws. A fixing washer should be used to avoid the screw pulling through the board.
How do I plaster onto wood wool board?
Please refer to the application guide for the specific plaster that you are using or call for advice.Can I attach glass fibre mesh to boards or do I have to embed it in the plaster, and can it be cut down as a scrim?
Glass fibre mesh should be pushed into a tight first coat (not directly onto the boards) and then the rest of the first coat applied over it. This prevents movement of the mesh. We would recommend that mesh is used across the whole area as oppose to simply scrimming the joints.
How do I skim onto old plaster?
Remove old limewash and sand off any wall papering residues. If a conventional paint has been used this must be removed. A devil float should be used to key the old plaster and slurry coat made from finish plaster and water and applied with a brush. You should then apply your skim with finish plaster applied in 2 tight coats of 1.5mm thick.
Can I apply lime plaster to metal lath?
If you have to but make sure it is stainless steel and is fixed with stainless steel fixings. Both Expanded Metal Lathe and Rib Lathe can be used but we would only use them when there is really no other alternative. Make sure the base coat is very well haired as the sharpness can disturb the nibs of the plaster causing the plaster to fail, hair will help give it strength.
Do I need to remove all old plaster?
It is often the case that unnecessary damage, waste and energy is used removing perfectly good old lime plasters. It is perfectly possible to patch in to these old plasters and thereby retain some of the original fabric of the building.
Can I lime render or lime plaster over concrete blocks?
Yes but there are some golden rules that should be adhered to and a hydraulic lime plaster is recommended as opposed to a fat lime plaster.
I have lime plaster left over, can it be re-used?
Yes, you can replace the unused plaster in buckets or sealed bags and store it dry and frost-free. You will be able to knock it up again when required, it will get harder over time and require more knocking up but it is perfectly possible.
Why do I need to protect lime work?
Lime products need to carbonate (not just set) which they need to do by absorbing Carbon Dioxide in the presence of moisture. It is therefore important to create the correct conditions for carbonation which comes through experience but is vital to the success - refer to the application guides for each product for details on protection - it is one of the most important points to ensure a successful result!
Different limes, different applications, different backgrounds (even in the same building), different times of the year and different elevations on the same site will all require careful attention and possibly different measures.
Most of the failures that we see are down to a lack of appropriate tending to aid carbonation as even a poorly specified/selected lime type can actually succeed if applied and cared for appropriately after all we did not historically have the range that we have now! As a result, we concentrate on this particular aspect on our training courses and in our application guides and are happy to discuss any aspect of it with our customers - call 01874 611350! We want your job to succeed and most do!
gives an accurate mix therefore removes the potential for any mixing errors. 
Premixed Fat Lime Plaster
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