by
Joel Hirshberg Originally published June 10, 2013 in the Green Home Guide, a service of the U.S. Green Building Council

Q: Oil Based to Water based? Hello, I would like to repaint my dining room, however I have been informed that the wood-paneled walls in the room have been previously painted with an oil-based paint. I am only comfortable using water-based products in my house and specifically, those with low or NO VOC's and chemicals. I am pregnant and have a toddler as well. My painter has informed me that there is no way to paint over oil-based paint without using an oil-based primer or some similar product. Is this true? Any guidance would be greatly appreciated. Thank you so much.
—Asked by Erica Pitman, Los Angeles, CA

A: Your painter is partially correct.

Transitional primers

You do need a primer, but if you wish to use a water-based zero VOC paint, then you need a transitional primer that will encapsulate the paint below and allow for good adhesion. It will not be made with oil as he suggested as almost all oil based primers contain petroleum-based solvents which are not good for your health.

Transitional primers are available everywhere, but even the water-based primers may still contain toxins. They may claim to be low or no VOC but you have to read the MSDS or consult with the technical people who make the product. Material Safety Data Sheets (MSDS) are not easy to read and are not very transparent. Proprietary ingredients (which can be toxic) are not required to be disclosed, nor are ingredients less than 1%, nor are unknown hazards (which amount to 98% of all chemicals).

Green lables

So who do you trust? Can you rely on green labels? Perhaps. There are now over 200 green labels which many provide some indication of safety, but most rely heavily on MSDS as their basis for determining safety. As we have seen above, that may not be reliable. Some are third party certified which is best, but many are not. Unfortunately, you have to do some serious research to find out what criteria is used for each label which is an undaunting task for any consumer.

As a supplier of green building materials, we use MSDS as a starting point, but we also test our own products and rely heavily on the experience of our chemically sensitive customers which make up 20% of our customer base. They act as yellow canaries and help us detect any possible hazardous ingredients that MSDS might be hiding.

Recommendations

So far, we have found two transitional primers that we like: AFM Safecoat Transitional Primer and (the sadly no longer available) Mythic PRIME interior/exterior all purpose stain blocker. There may be others, but based on our experience over 23 years, these two work the best at transitioning from oil to water without VOC’s, carcinogens or off-gassing.