Wrong paint used on MDF causing fumes

Hi, unusual one this, my solution would be to repaint affected units with zinnser bin sealer then finish with u your farrow and ball , should stop the smell .

You could try sanding it back to bare mdf then applying the correct primer, but if the smell is still there then it would have to be starting again. Unfortunately with certain paints there is a strong smell and they don't dry effectively in time. Personally I think it would be easier to start again as getting all the paint off would take a lot of time x

I would rub down with light sand paper reseal with Zinsser make sure it drys probably then repaint with your farrow and ball top coat

Because you used an oil-based undercoat (the Berger white undercoat) and then sealed it with a water-based topcoat (Farrow & Ball Dead Flat), the oil-based solvents are trapped. They cannot evaporate through the water-based "plastic" film on top, so they are slowly leaking out, causing that persistent, strong smell even a month later. ​Here is exactly how to fix it: ​1. Why Home Remedies Aren't Working ​Onions, lemons, charcoal, and bicarbonate of soda only absorb odors that have already reached the air. They do not address the source: the wet, uncured oil paint trapped under your topcoat. As long as that gas is trapped, the smell will remain. ​2. The Solution: Seal or Strip ​You have two realistic options to resolve this permanently: ​Option A: The "Sealer" Method (Easiest) Apply 1–2 coats of Zinsser B-I-N. This is a shellac-based primer specifically designed to block odors and "seal in" problematic substrates. Unlike your current topcoat, shellac creates a vapor barrier that prevents the solvent smell from escaping. ​Note: After sealing with B-I-N, you can re-apply your Farrow & Ball topcoat safely. ​Option B: The "Strip" Method (Safest for the MDF) If the paint feels slightly soft or "tacky" when you press a fingernail into it, it means the paint will never fully cure. In this case, you must sand or scrape the units back to the bare MDF and start again with the correct water-based MDF primer. ​3. Immediate Steps ​Stop the Heat: While heat usually helps paint dry, in this case, it is expanding the trapped gases and making the smell more intense without actually curing the underlying paint. ​Ventilate, don't Purify: Most air purifiers cannot handle the volume of VOCs (Volatile Organic Compounds) coming off wet oil paint. Open windows to create a cross-breeze rather than relying on a machine.

I wouldn't assume the smell is just trapped solvent, as Berger undercoats vary. Check the exact product on the tin and its drying guidance, then ask Berger and Farrow & Ball whether the two paints are compatible. If the undercoat is still soft or tacky, don't seal over it yet. Keep the room well ventilated and get the makers' advice before sanding or stripping. A sealer won't fix a coating that hasn't cured properly.