Prosoco Weather Seal Siloxane PD masonry sealer

Siloxane PD: what we stock

What does Siloxane PD do?

PD stands for predilute: it goes on as packaged, with no mixing. It is a penetrating masonry sealer, not a coating. It won't change how the wall breathes or trap moisture behind it. Because it is alkaline stable, it can go on new concrete 14 to 28 days old.

Prosoco's third-party test results show water absorption cut by about 89% on concrete and 96% on brick. It also resists water through shrinkage cracks of 0.02" or less. It will not keep water out of larger cracks, defects or open joints, so pointing and caulking come first.

How far does Siloxane PD go on each substrate?

Coverage from Prosoco's product data sheet, in square feet per gallon. Rates depend on texture and porosity, so a test area sets the real number.

Job conditions from the data sheet

• Apply to clean, visibly dry, absorbent masonry. New and repointed walls get cleaned first.
• Air and surface temperatures 40 to 95 F during use and for 8 hours after.
• Dry to the touch in 1 hour. Keep rain off for 6 hours. Full water repellency in 72 hours.
• Low-pressure spray under 50 psi, applied wet-on-wet from the bottom up. Brush or roller for small areas.
• Above grade only. Prosoco does not recommend it below grade, and wall tops must be capped first.
• Water-based, low odor, under 30 g/L VOC, 1 year shelf life. Protect from freezing.

Stone treatments for limestone and marble

Siloxane PD is not for calcareous stone. For those jobs we stock Prosoco's Natural Stone Treatment, a modified siloxane repellent for limestone, marble and most traditional masonry. It comes in a solvent-based 1 gallon and a water-based WB 5 gallon. Gloss N Guard is different: a clear coating that dries to a high gloss on tile, pavers and terrazzo.

Questions about Siloxane PD

What is Siloxane PD used for?

Siloxane PD is a clear, penetrating water repellent for above-grade concrete, brick, most masonry, stucco and manufactured stone. It keeps water from soaking in, which helps prevent cracking, spalling and staining, while letting the wall release moisture. It is sprayed on as packaged, with no dilution.

Can you paint over Siloxane PD?

Prosoco says to test first. Paint adhesion can be improved by pressure-rinsing the treated surface and letting it dry. Some cementitious coatings, plaster and stucco may not bond well to treated masonry, so Prosoco recommends installing them first and letting them cure before applying Siloxane PD.

How much area does Siloxane PD seal per gallon?

Per Prosoco's data sheet, 150 to 200 sq ft per gallon on concrete, 50 to 175 sq ft on fired clay brick and tile, and 75 to 125 sq ft on unpolished sandstone. Texture and porosity change the rate, so run a test area to confirm coverage before ordering for a large job.

How long does siloxane last?

Prosoco's data sheet estimates the service life of Siloxane PD at more than 10 years. Real life depends on exposure and surface prep. Applying to wet masonry reduces penetration and shortens service life, and the repellent will not bridge cracks wider than 0.02".

Last updated November 2, 2026

Yankocy sells Prosoco water repellents wholesale to mason yards and dealers. Buying for your own home? Your local lumber or mason yard can order it for you.

Siloxane PD data sheets and sources

• Prosoco Siloxane PD product page
• Siloxane PD safety data sheet (PDF)
• Weather Seal Siloxane PD product data sheet (PDF)
• Natural Stone Treatment product data sheet (PDF)
• Natural Stone Treatment WB product data sheet (PDF)
• Gloss N Guard product data sheet (PDF)

Related to Siloxane PD

• Sure Klean 600
• Thoroseal
• Anti-Hydro
• All masonry coatings & cleaners