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Rainguard Micro-Seal is a silane/siloxane penetrating water repellent from Rainguard Brands. It’s sold as a concentrate you dilute with water, and in ready-to-use versions, for concrete, brick, block, stone and stucco.
| Type | Penetrating water repellent |
| Chemistry | Silane/siloxane with Micro-Lok; solvent-free concentrate |
| VOC | Zero (per manufacturer) |
| Mixing | 1-gallon concentrate makes about 10 gallons (9 parts water to 1); super concentrate mixes 19:1 |
| Finish | Invisible, non-yellowing, vapor permeable |
| Warranty | 10 years (Micro-Seal); 20 years for Micro-Seal HD |
What It Is
Micro-Seal forms a water-repellent barrier inside porous surfaces that still lets moisture vapor escape. Rainguard markets it for efflorescence control and for protection from mold, mildew, salt and freeze-thaw damage. The heavier-duty Micro-Seal HD adds oil and gas stain resistance.
Pros
- Concentrate keeps shipping weight and cost down
- Zero VOC and low odor
- Doesn’t change the look of the surface
- Can also be used on fresh concrete to slow moisture loss while it cures
Cons
- Diluted strength is lower than ready-to-use high-actives sealers, so follow mix ratios carefully
- Standard Micro-Seal isn’t an oil or stain repellent
- Clean off stains and old coatings first, or the sealer can’t penetrate
Who Should Buy It
It’s a good fit for homeowners and property managers sealing large areas of brick, block or stucco who want an invisible, low-odor product. For high-traffic driveways, compare it with the picks in our best penetrating concrete sealers guide.
How we reviewed this product: this is a research-based review built from the manufacturer’s technical data sheet, current retail listings and owner feedback. We have not run our own hands-on tests of this product. Details were checked in October 2026; always follow the current label.