Painting Over Old Gloss With Water-Based Paint
You don’t have to keep using oil-based gloss just because that’s what’s already on your doors and skirting boards. A water-based finish can go over it, provided the old coating is sound and you prepare it properly. The catch is that a smooth, shiny surface gives fresh paint very little to grip.
When you’re looking at water based paints, choose a product intended for the surface you’re decorating. The emulsion left over from painting the bedroom walls isn’t automatically suitable for a door. Water-based gloss, satin and eggshell finishes for woodwork have different jobs from ordinary wall paint. Woodwork needs a finish that tolerates handling.
Give the old paint some attention
Have a close look before reaching for the sandpaper. Paint that’s peeling or lifting needs dealing with first, because a new coat will only be attached as firmly as the old one beneath it. There’s no point carefully painting over a loose edge that will come away at the next knock.
Cleaning comes before sanding. Door frames collect grease from hands, and skirting boards gather rather more than dust, particularly near a cooker. Use a suitable cleaner, follow its instructions and rinse away any residue. Once everything is dry, you can see what you’re actually working with.
For very old paintwork, check for lead before disturbing it and get advice about safe preparation if you’re unsure. Where sanding is appropriate, the aim is usually to dull the shine and smooth rough edges. You don’t necessarily need to strip sound paint back to bare timber.
This is where the primer instructions become useful. Some adhesion primers are designed for glossy surfaces without full sanding, while other systems need an abraded surface. Check that the primer suits both the old coating and your chosen topcoat. A tin labelled ‘primer’ isn’t a promise that it will work on everything.
If you’re repainting several doors, try the primer and topcoat on one discreet patch first. Let it dry and harden according to the instructions before checking adhesion. Discovering a problem here is much less dispiriting than finding that every door in the hallway needs to be done again.
Painting without fighting the brush
Once the preparation is finished, use the brush recommended for the paint. A good synthetic brush is commonly specified for water-based woodwork finishes. Work in manageable sections and resist going back over an area that has started to set. Continually brushing it can leave marks instead of smoothing them away.
If the first coat looks patchy, check the recommended coverage and number of coats before trying to fix it by laying the paint on heavily. A second properly applied coat may be exactly what the system requires. Corners and mouldings need particular care because excess paint can collect there.
Follow the drying interval before recoating, even if the surface feels dry sooner. Once the job looks finished, it still needs some care while the coating hardens. Give doors time before shutting them firmly against their frames, and leave the enthusiastic cleaning until the manufacturer says the finish is ready for it.
