Question

I am building a house and wanted to use plaster instead of paint to avoid all the toxins. The plasterers decided to use a a coat of primer o

Asked by Minka M. Robinson
Santa Barbara, CA

The plaster is not on yet and I am wondering if i can take the paint off or use an ozone machine or cover it up with no VOC pain or sealer or should I wait until the plaster is on and then seal it?

Answer

Elizabeth DiSalvo

Answered by Elizabeth DiSalvo

Norwalk, CT

Trillium Architects

December 7, 2011

Hi Minka, Good question. As green architects we spec exclusively No-Voc paints and finishes, of course, but every so often there are situations that occur that cannot be helped. Either a subcontractor makes a mistake (like your's did it seems) or there is a situation that demands a finish or treatment that is not available in a No-Voc product. In your situation I would leave it be. I assume that the job is done, and that paint is dry. If it has aired out extremely well and been a dew days the primer has most likely done most of its off-gassing. If it has net been aired out well, but is dry, I would air the room/ house out very well. Turning on the heat helps as does opening the windows and doors wide for hours during the middle of the day. You don't want to expose the house to a lot of humidity from outside (not sure what the weather is like right now in SB,CA). But definitely get some airflow going with fans and maybe some heat. Once the primer has been dry and aired it should be fine. It is now in a latent state and off-gassing will be negligible if happening at all. You will doubly protect yourself by plastering over the primer. There is a chance that wetting the primer while plastering may activate some of the primer's VOC potential, but if the team priming the walls is professional they would have used a primer whose very purpose it is NOT to be penetrated by the moisture of the plaster (as this would make the plaster more likely to pull the primer away from the wall and thus allow the plaster to 'fall off'.) The idea behind priming the wall first is to kill staining and to provide a good base for the plaster to adhere to. The primer should hold up to the plastering (not get activated by the moisture) and therefor not release significant VOC's. I would leave the primer in place. You would probably release more VOC's by removing it than by leaving it and by covering it with plaster you are protecting it from flaking, chipping or other physical damage that may release VOC's. I think if you then take care to paint or coat the finished plaster with a No-VOC product (or simply leave the plaster as is if that is an aesthetic option.) then you are fine. We have an American Clay plaster wall in our office and our installer was quite finicky about having a good primer coat underneath (ours was No-VOC). And it is left unsealed. Beautiful and prefect for 5 years now. Not a chip or flake. The primer layer is important. Good luck! Elizabeth DiSalvo

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