Once again we are here to learn 
more about American Clay products. This month we'll be talking about primers. Paint primers, and American Clay's Sanded Primer Elite.
As most of you know, American Clay's sanded primer is a PERMEABLE primer. This means that water (or moisture in the form of vapor) will readily pass through it. This is a good thing in terms of mold resistance and humidity buffering, but it is not good in terms of isolating the substrate from American Clay plaster.
We have been recommending that you prime all joint compound with a good quality primer, and in practice, why not prime the entire surface? This evens out suction rates and makes your application easier, if you use the right primer.
A drywall “prep” primer is much like out Sanded Primer Elite and often is quite permeable. As we know, this can cause problems with installation of American Clay. What happens (as with Sanded Primer Elite) is that moisture from the application of American Clay passes through the primer and either breaks the bond that the paint has or loosens up the joint compound underneath. This causes failure or delamination. This happens more readily with Mud Glue because of the way that it bonds to the substrate.
To avoid this, use a transitional primer. AFM safe-coat, American Pride, and Mythic all have 0 VOC transitional primers which are good for isolating the substrate from American Clay plaster. Being an environmentally conscious company, we recommend using a 0 VOC product. Sherwin Williams Harmony and Benjamin Moore’s Aura have been used successfully also, but we have heard people say that they take a long time to cure (dry thoroughly).
As always, you should wash walls and remove any dust with a solution of 10% penetrating sealer and 90% water before applying any primer.
When going over existing painted walls, it generally does not need an additional coat of primer. That said, we often see poor paint jobs (walls not cleaned before paint etc…) that look good, only to find that after American Clay plaster is put on that the paint fails. In those cases, it is always safest to prime the walls with a transitional primer.
As I mentioned earlier, Mud Glue tends to accentuate these issues because of the way that it bonds. When it etches the substrate, it often allows water to pass through it causing the mentioned problems. Using Sanded Primer Elite, or ADD MIX can alleviate this problem.
We want you to be successful during application so PLEASE feel free to call or email anytime with questions. We won’t answer the phone at midnight, but you can always leave a message, and sometime we will answer at 8 on a Saturday night but not usually. We usually answer the phone during normal business hours except when we’re on the phone with someone else or in a meeting. Sometimes we get to the office early and you can try then, but sometimes we can’t answer the call until 9 or so. Often we are here late, but sometimes we are so busy that we stop answering the phone at 4 or so. We don’t close for lunch, but sometimes everyone is gone so the people here are on the phone then and can’t get to your call, but we usually answer whenever you call. We’re great about returning emails, except when it’s late, or we’re travelling or the server is down. Sometimes your emails go to our junk folders and we try to check those, but usually it’s only once a week. Anyway, we’re here all the time to help you… except when we’re not.
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