Primers and EPDM
As we bring our series on proper primer usage to a close, we will look at primer usage on EPDM substrates. As you may already know, EPDM is typically known as the most stubborn substrate when it comes to silicone adhesion. If it’s too new, the silicone may not hold. If it’s too old and dirty the silicone may not hold. EPDM gave silicone experts a headache, until the right method was finally discovered.
P-120 Rinseable Cleaner
Lucky for you, PM has this method down to a science. The first key to silicone application over EPDM is to use our P-120 rinseable cleaner. Although not technically a “primer”, this cleaner is definitely necessary before coating on EPDM. After power washing the roof, P-120 is applied onto the EPDM. All you do after that is let P-120 sit for ten minutes and then rinse it off. This quick step will help our silicone adhere very well to the EPDM.
If, after the roof has been washed and cleaned, adhesion tests are still showing less-than-desirable performance, P-151 primer may be used to offer optimal strength. In some extreme cases, when additional adhesion is necessary, P-151 can be used to offer maximum hold. Between P-120 and P-151, you can guarantee great PM silicone adhesion on EDPM!
If you are worried about bleed through (like on mod bit, asphalt, gravel BUR roofs) you can also use our P-110 EPDM Bleed Block primer. This will ensure your roof color is not tainted by yellow coloring due to EPDM bleed through. In most cases, this primer is only necessary on new EPDM. Make sure you keep this in mind if you are putting in patches of new EPDM though. We would hate to see yellowing in certain areas when a simple and quick primer application could keep the top coat looking great.
Since EPDM can be so problematic, we recommend that you speak to your regional manager before using our silicone on this substrate. Our Regional Managers can offer free adhesion tests and demonstrations. They are more than happy to walk you through the process. You can find your regional manager here.
Thank you for reading our series on PM primers. We hope you learned a thing or two about proper silicone and primer usage and will be better prepared to win business in the future!