Frequently Asked Questions

1. How strong should a limewash mixture be if it is to be painted with Skalcem 100?
2. How soon can you paint over a newly plastered wall?
3. Can you use Skalcem S 2000 to lime wash new masonry?
4. Can you use Skalcem S 2000 to lime wash masonry with raked joints?
5. Why does silicate paint peel in spots on new limewash?
6. How do you renovate the facade of a lime/sandstone house?
7. My house was painted with Skalcem 100 Skagen Yellow. It has white blooms. How come?
8. Can you use Skalcem 100 on Cempexo?
9. How do you paint with Skalcem 100 on smooth concrete masonry units?
10. How do you maintain the colour on Skalcem S 2000?
11. Can you paint on whitened surfaces?

1. How strong should a limewash mixture be if it is to be painted with Skalcem 100?

There are just as many "recipes" on limewash mortars as there are bricklayers. However, in general, it is our experience that you should stick to factory-made dry mortars. These have low lime content and are mixed with cement in a ratio that ensures uniform strength in the entire limewashed layer.

2. How soon can you paint over a newly plastered wall?  

It is commonly accepted that you should wait one year before painting a newly plastered house. This is not necessarily the case always. If you would like to paint your house with Skalcem 100, you can "make do with" waiting until the plaster has cured (20-28 days). This type of paint tolerates moisture in the underlying layer. If you are using Facade Silicate, make sure that the underlying layer is completely dry before you start painting. If the plaster was applied early in the year, you can usually paint with Facade Silicate after the summer holidays.

You should still adhere, however, to the waiting period of one year if you wish to use emulsion paints and other "non-mineral" paints. These are pH neutral and consequently do not tolerate being applied on to new plaster with a high pH value. This pH value becomes lower the older the plaster is.

3. Can you use Skalcem S 2000 to lime wash new masonry?

Masonry must be fully cured before you paint with Skalcem S 2000, i.e. it must be at least 28 days old. The wall mortar must be able to breathe throughout the entire curing process. In addition, even though Skalcem S 2000 is a vapour permeable product, it would still reduce the access of air to the mortar, so that this may become porous with frost damage as a result later on. You should also note that if the masonry was built during a time of year with high moisture, you might risk getting efflorescence on the masonry when this dries. This efflorescence will pass through Skalcem S 2000, but leave some blooms that can scar the final result. To avoid this, you should leave the masonry for one year before limewashing it. You will then be able to brush off the efflorescence with a hard broom and in this way avoid scarring the facade.

4. Can you use Skalcem S 2000 to lime wash masonry with raked joints?

If the joints are more than 10 mm deep, they should be filled with regular building mortar. When the mortar has cured (28 days old), you can lime wash it with Skalcem S 2000. Please note, however, that if you want to rub down the wall using a dark colour, the joints should be completely dry. Otherwise, you may see significant variations in colour between the Skalcem layer on the wall and that in the joints. The risk of this can be reduced by generous wetting. If the joints are 5 mm or less, you can use Skalcem S 2000 with 20% added quartz sand (grain size 0.4-0.8). In this way, you avoid shrinkage cracks around the joints.

5. Why does silicate paint peel in spots on new limewash?

Silicate paint must be able to penetrate into the plaster where it forms a reaction with the underlying layer, creating an insoluble fusion with the plaster. If there is moisture or brick salt in the underlying layer, these prevent the paint from penetrating into the underlying layer. This means that no reaction is formed with the underlying layer, causing the paint only to dry on the surface. Since silicate paint contains no binders, it will begin to come loose and peel. This issue is rather easy to fix; brush the area thoroughly, make sure that there is no more moisture or salts in the underlying layer and then repaint it. It is advisable to paint the entire facade section (from corner to corner) to avoid any visible "paint spots".

6. How do you renovate the facade of a lime/sandstone house?  

Lime/sandstone is a very broad concept, varying in types, place of production and age/degree of wear and tear. It is thus difficult to provide any general guidelines. We recommend having the building inspected by one of our technical consultants who will then offer advice on a case-to-case basis. This inspection is free of charge (please allow up to 2 weeks wait time).

7. My house was painted with Skalcem 100 Skagen Yellow. It has white blooms. How come?

Skalcem 100 is based on white cement that cures and "retains" the colour. If any white blooms occur in the final surface, an error occurred in the curing process. Such curing errors may have various causes. The most common cause is if the facade is exposed to rain within the first 2-4 days after it has been painted. In this case, "chalking" occurs in the surface, i.e. the white cement that has not cured will show in the outermost part of the surface and cure there. This will result in a cosmetic flaw. In principle, there is nothing wrong with the surface itself. This problem often occurs in connection with low temperatures at night in the spring months. Another cause may be if the work is done at too high temperatures, which will retard the curing process because the moisture that the paint needs to cure evaporates. When the surface is exposed to rain, the uncured cement will produce white blooms. This problem may be prevented by wetting the surface afterwards with atomized water after 1-2 days if you notice that the surface is contaminated.

8. Can you use Skalcem 100 on Cempexo?  

Both products are cement-based, so there is no problem using Skalcem 100 on a surface treated with Cempexo.
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9. How do you paint with Skalcem 100 on smooth concrete masonry units?  

When you paint on cast concrete masonry units, make sure that they are free from mould oil. It is not necessary to wet smooth units beforehand. Instead, replace 1 litre of water with 1 litre of Beto binder for 10 kg Skalcem 100. This mixture will easily roll on to the surface. For smooth units, please expect two coats. If you would like to create some texture in the surface, you can add 1 kg sand for 10 kg mixed Skalcem 100.

10. How do you maintain your colour on Skalcem S 2000?  

When the colour of Skalcem S 2000 becomes "worn", refresh it with Facade Silicate thinned with 20% Facade Silicate Primer. In this way, you add new colour pigments to the surface without compromising the texture. At the same time, it is ensured that the surface is still vapour permeable. If your house is by the ocean, it may be necessary to maintain a cement-based surface. We thus recommend that you use Skalcem 100 for maintenance purposes, as other paint types do not tolerate the aggressive environment posed by the salty air.

11. Can you paint on whitened surfaces?

In principle, you cannot paint on whitewash. The paint will usually "pull off" the whitewash, causing the facade to peel. This often happens in winter where the whitewashed layer absorbs moisture from rain and high humidity. When this happens, the whitewash layer expands, the paint cracks and more moisture is allowed to penetrate behind the paint, which will then cause further peeling. Such peeling is seen mostly on surfaces exposed to direct water impact. It is thus a good idea always to clean your facades completely until all whitewash has been removed if you want to paint these surfaces.