Concrete Sealing 101
Q: We are using a sealer for decorative concrete curbing and were wondering if we are supposed to be thinning it with another product? As is the sealer is very thick and leaves bubbles on the curbing.
A: The sealer that you are using is likely a very high-solids product (30% or more). It could be thinned with Xylene solvent**. However, what is likely causing the problem is a combination of the following:
1. Application too soon after casting the curb can trap the “bleed water” in the concrete. This internal moisture can’t escape, causing bubbles. Try waiting a while before application.
2. Application of one very thick coat. Two thin coats is a best practice.
3. You may have small air voids in the cast concrete. As the sealer enters these voids, the air needs to escape but can’t. Therefore, “dress” the curb with a sponge float after the bleed has occurred to fill any voids prior to applying sealer.
Try these 3 possible solutions above before attempting to thin the product out, as thinning may cause adverse effects. If these variables fail to produce satisfactory results, you may want to try a lower-solids product. However you won’t get the gloss that you are used to having with the high-solids product.
A few other guidelines to keep in mind for concrete sealing:
- For existing concrete, thoroughly pressure-wash the surface and apply a degreaser if necessary. Allow to dry completely to avoid white blotches.
- A test section is recommended to ensure compatibility with any previously applied sealers, prior to final application.
- Do not apply in direct sunlight. Application should be early morning after dew is thoroughly dried. Successful applications will occur in the temperature range of about 60 to 70 degrees Fahrenheit. Avoid application in mid day or afternoon.
- Allow coats a minimum of 2 hours to dry before recoating.
- Allow 24 hours before vehicle traffic.
- When applying any flammable liquids, make sure the area is well ventilated and all sources of ignition are extinguished.
- Immediately close any unused sealant containers and store in a cool dry area.
- Always wear appropriate protective gear.
Note: None of this information is intended to supersede the manufacturer’s application instructions. Please consult the product’s MSDS or Technical Data Sheets for specific application instructions.
And as always, contact your local BW Representative for more application information and a list of sealers that are right for your project.
** Make sure to consult Brock White before thinning any sealers with a Xylene solvent to ensure the mix conforms to VOC regulations.
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