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DOWSIL™ 88 Additive

A 98% actives silane/siloxane concentrate. It can be used in polar and non-polar solvent containing acrylic formulations to improve water repellency.


  • Solvent-free and APEO-free
  • Contribute <10 g/l VOCs when used at up to 5% by weight
  • Reduce water absorption at only 1% addition by weight
  • Negligible impact on water permeability, even at 5% addition by weight
  • Maintain paintable surfaces when used at up to 5% by weight
  • Effective in solvent-based decorative paints

High-performance additives for improved water resistance in decorative coatings

Power Up Your Coatings

Do you want to increase the water resistance of your wood, masonry and other porous decorative coating formulations, but haven’t yet because of the high addition levels required for currently available silicone products? DOWSIL™ 88 Additive can help.

DOWSIL™ 88 Additive is a silane/siloxane blend with a VOC content of 73 g/l. It is effective at improving water resistance both in acrylic emulsion paints containing polar solvents and in solvent-based systems. This additive improves water resistance by creating a hydrophobic silicone network in the paint that repels water but is permeable to water vapor coming from the substrate. As a result, water penetration is reduced while cracking and blistering are minimized.

Performance at additive levels: reduced water absorption

Water absorption (W24) through a paint film is measured as a function of time. The lower the water absorption of a coating, the more water resistance the film offers and the greater protection it provides. Even at only 2% addition by weight, DOWSIL 88 Additive provides reduced water absorption.

With DOWSIL™ 88 Additive, addition at 5% shows even further reduction in water absorption, while a competitor silicone resin provides no additional protection when the addition level is increased from 5% to 10%.

Figure 1: W24 of an acrylic-based emulsion paint with and without DOWSIL™ 87 (A) and 88 (B) Additives and vs. a competitor silicone resin emulsion.

Graph: Acrylic-based emulsion paint with and without DOWSIL™ 87 and DOWSIL™ 88 Additives and vs. competitor silicone resin emulsion

The best of both worlds: Excellent water vapor permeability

While DOWSIL™ 88 Additive reduces water absorption, yet allows water vapor coming from the substrate to pass through the silicone network, preventing the cracking and blistering that can be a problem with some decorative coatings. Water vapor permeability is reported as the Sd value and is a function of the water vapor transmission rate.

Even in a high-PVC paint formulation that has excellent water vapor permeability DOWSIL™ 88 Additive has only a minimal impact on the Sd value when used at a high addition level (Figure 2).

Figure 2: Sd of water of a high-PVC paint formulation with and without DOWSIL™ 87 (A) and 88 (B) Additives.

Graph: High-PVC paint formulation with and without DOWSIL™ 87 and DOWSIL™ 88 Additives


For more information

To learn more about these products, download the DOWSIL™ 87 Additive and DOWSIL™ 88 Additive Information Sheet.

View Document ►


These values are typical properties and are not intended for use in preparing specifications.

  • Color Clear to Hazy
  • Nonvolatile Content 98 %
  • Shelf Life 720 Days
  • Specific Gravity @ 25C 0.967

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DOWSIL™ 88 Additive
No Technical Data Sheets are available for this product
Please Contact Dow for additional information.

DOWSIL™ 88 Additive

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DOWSIL™ 88 Additive
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