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KLAAS COATINGS

Technical

FAQ's

General questions and answers on Si-Rex03 silicone resin emulsion paint.

1. Why should one coat concrete and masonry facades with a breathable (water vapor permeable) coating system? Answer

2. How breathable is Si-Rex03? Answer

3. Why is it such an advantage that Si-Rex03 is permeable to water vapor yet at the same time water-repellent (beading effect)? Answer

4. How long will Si-Rex03 maintain its beading effect? Answer

5. What makes Si-Rex03 so durable? Answer

6. What exterior coating system will reduce mold and mildew growth? Answer

7. Is Si-Rex03 mineral or organic? Answer

8. Have silicone resin emulsion paints proved successful over the long term? Answer

9. Can all kinds of paint be overpainted with Si-Rex03? Answer

10. Can Si-Rex03 be applied directly to facades with salt damage? Answer

11. What is the function of a silicone-based primer? Answer

12. Why is it advisable to coat exterior insulation and finish systems (EIFS) with Si-Rex03? Answer

13. Can Si-Rex03 be readily overpainted? Answer

14. Must an old coating of Si-Rex03 be stripped off before a new coating of
Si-Rex03 can be applied? Answer

15. Why is it worthwhile using Si-Rex03 rather than cheaper alternatives? Answer

16. Are special contractors or skills required to apply Si-Rex03? Answer

17. Can Si-Rex03 be matched to other color charts? Answer

18. What is difference between oxide pigments and organic pigments? Answer


1. Why should one coat concrete and masonry facades with a breathable (water vapor permeable) coating system?
All coat concrete and masonry facades contain some flaw (e.g. hairline cracks, porous substrate); these are weak spots where moisture can penetrate into the substrate. The substrate must be able to dry out whenever ambient conditions permit otherwise spalling or other deleterious damage will occur. In addition, dry substrates do not promote the growth of mold and mildew.
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2. How breathable is Si-Rex03?
Si-Rex03 is a mineral-like coating and is accordingly just as breathable (water-vapor permeable). The reason is its microporous structure that permits free movement of gases. In tests conducted Si-Rex03 recorded 67.9 perms.
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3. Why is it such an advantage that Si-Rex03 is permeable to water vapor yet at the same time water-repellent (beading effect)?

Because the coating is permeable to water vapor the substrate is able to breathe; the beading effect prevents water absorption. The combination of these two properties makes silicone resin emulsion paint the superior coating system for concrete and masonry facades with added benefits of extremely high durability and dirt repellent effect.
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4. How long will Si-Rex03 maintain its beading effect?
The beading effect of silicone resin emulsion paints is apparent during weathering (rain, snow etc.) and is retained throughout the coating’s service life.
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5. What makes Si-Rex03 so durable?
Si-Rex03 owes its great durability to the properties of low water absorption combined with high water-vapor permeability. These properties are due to the silicone resin binder that forms a strongly hydrophobic (water-repellent) network yet is just as mineral in nature as quartz.
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6. What exterior coating system will reduce mold and mildew growth?

Dry facades are less prone to attack by mold and mildew than damp ones. Mineral-type coatings are less susceptible than thermoplastic (e.g. acrylic) coatings. Silicone resin emulsion paints keep facades dry; they are non-thermoplastic, mineral-type coatings and thus provide protection against the growth of microorganisms. For facades at risk (e.g. high heat, high humidity), Si-Rex03 is available with additional protection against microorganisms.
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7. Is Si-Rex03 mineral or organic?
The binder in Si-Rex03 comprises 50 % mineral-type silicone resin and 50 % polymer emulsion. The paints thus combine the useful properties of organic and mineral coatings in a single system.
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8. Have silicone resin emulsion paints proved successful over the long term?
Silicone resin emulsion paints have been used successfully for 40 years. More than a million buildings all over Europe have been coated with these paints, and many of them have endured over 20 years without needing any further renovation – let alone repainting.
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9. Can all kinds of paint be overpainted with Si-Rex03?
Provided they are suitably prepared and cleaned, all kinds of paint can be overpainted with Si-Rex03 including firmly adhering emulsion coatings (see also Question 15). However, to avoid compromising the Si-Rex03’s breathability, old coats of emulsion paint must be stripped off or removed mechanically.
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10. Can Si-Rex03 be applied directly to facades with salt damage?
Substrates with salt damage must always be properly repaired first; remove any damaged substrate, effect repairs then apply Si-Prime or Cremsil. Then the substrate can be painted with Si-Rex03.
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11. What is the function of Si-Prime or Cremsil?
The paint/substrate interface is the vulnerable area for any coating system. Si-Prime or Cremsil improve the effectiveness of the paint coating by creating a dry zone under the paint and thus prevent substances such as alkalis and salts within the substrate from reaching the surface and protect the coating.
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12. Why is it advisable to coat exterior insulation and finish systems (EIFS) with Si-Rex03?

EIFS, in particular, benefit from all the special properties of Si-Rex03: water repellency, water-vapor permeability, dirt repellency, stress-free drying, easy processing, etc.
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13. Can Si-Rex03 be readily overpainted?
Yes. Self priming paints or adhesion modified acrylic paints containing a wetting agent will adhere to Si-Rex03. Some polyurethane without wetting agents have experienced issues; silicate paints and whitewash will not adhere.
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14. Must an old coating of Si-Rex03 be stripped off before a new coating of Si-Rex03 can be applied?
No (see also Question 9). Simply clean the facade, remove any loose particles and, ideally, treat any exposed substrate areas with Si-Prime. This also applies to old mineral coatings; silicate paints, organosilicate paints and whitewash.
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15. Why is it worthwhile using Si-Rex03 rather than cheaper alternatives?
The quality of an exterior architectural paint is measured by the length of time it protects the substrate from external influences and keeps it looking perfect. Silicone resin emulsion paints are unparalleled in this respect and makes them much more economical in the long term.
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16. Are special contractors or skills required to apply Si-Rex03?
Si-Rex03 is formulated to make application as forgiving as possible; so no specialist training is necessary. Any experienced and reliable painting contractor will be able to the product.
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17. Can Si-Rex03 be matched to other color charts?

Yes. However not all colors can be matched as only oxide based pigments – that create mainly “earthy” colors – are used. Colors such as bright yellows, lime greens, bright reds, oranges and purples are not possible.
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18. What is difference between oxide pigments and organic pigments?
Only oxide pigments are used in Si-Rex03. Oxide pigments do not break down with UV exposure; organic pigments do break down with UV exposure. Organic pigments are more suited to interior applications however fade with long term exterior exposure. Oxide pigments tend to be more “earthy” colors compared to bright and strong organic pigment colors.
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