What happened to my silicone roof coating?

By Progressive Materials.

With oil- and asphalt- based roofing, there will often be yellowing over time. Learn why this happens and what can be done about it!

A fresh roof coating is a beautiful sight. Not only is it a comforting reassurance that the entire roof system is protected and prepared to withstand the elements, but the clean, white finish breathes new life into the appearance of the roof. But oil- and asphalt- based materials like modified bitumen and tar, that pristine white coating often begins to yellow over time. Learn from the experts at Progressive Materials (PM) why this happens and what can be done about it.

Oil-/asphalt-based roof’s problem  

The main issue with oil/asphalt-based roofs is that these substrates have heavy oils in them. These oils will always leach out of the oil/asphalt and work their way to the surface. Although this leaching will not affect the adhesion of PM silicone in any way, it can create a yellowing effect to the coating. You could see this on newer EPDM roofs as well — typically five years of age or younger. Fortunately, PM has a solution to mitigate yellowing on these roof types. The photo is what yellowing can look like if silicone is put down without a primer on mod bit. PM’s primers prevent this yellowing from taking place.

The solution

PM’s P-160 Asphalt Bleed-Block Primer and P-110 EPDM Bleed-Block Primer prevent this discoloration if applied before the silicone topcoat. These primers block these oils from leaching, or bleeding, into the silicone will prevent the yellowing altogether. Our bleed-block primers and intended to be sprayed, rolled or brushed on with ease. Once applied and dry, the silicone topcoat can be sprayed or rolled onto the roof. The primer will offer protection from yellowing, and the roof will be seamless and waterproof with multiple other benefits.

Conclusion

Oil- and asphalt-based substrates are almost always great candidates for a silicone roof restoration. PM silicone adheres great to these substrates and can help restore them and keep them watertight. If, however, the roof is in a high visibility area or the building owner wants to retain their bright white coating, this oil bleed-through can stain the coating. Thankfully, our full line of silicone products, primers and accessories has everything you need to restore these roofs and keep them beautiful for decades!

Original article and photo source: Progressive Materials