Before you dip-strip an old Edinburgh door

Then it dries

The door comes back without its layers of paint. The grain is visible, the edges are sharp and it photographs well.

I have seen stripped doors split, twist and open at the joints. Filler leaves with the coating and the defect underneath becomes visible. Sometimes the timber is ordinary, patchy softwood rather than the even board the owner had in mind.

I have not followed every door through careful neutralising, controlled drying and prompt refinishing. My experience does not prove that every competent stripping job fails. It is enough for me to ask what happens after the tank, not only what the door looks like when it comes out.

Was the door meant to be bare?

SPAB notes that old softwood doors were generally intended to be painted. Its guidance on old doors also warns that stripping can raise the grain and soften glue.

Traditional doors are assembled from rails, stiles, panels and glued joints. SPAB’s guidance for timber windows says joinery should not be immersed in caustic soda because it can deform timber and weaken joints. A door is not a window, but I would take that warning seriously before immersing another piece of assembled old joinery. The SPAB repair note sets out the concern.

Once it is back in the flat, the timber continues to exchange moisture with the surrounding air. The Forest Products Laboratory explains how wood moisture follows relative humidity and temperature, while coatings slow rather than stop the exchange. The Wood Handbook covers the material behaviour.

A tenement door may have a warm room on one side and a cooler common stair on the other.

Old paint and lead

The Health and Safety Executive says removing old coatings can create lead exposure in properties built before the 1980s. For sound paint, its guidance includes wet abrading to provide a key and overcoating. For paint in poor condition, it points to controlled methods such as chemical stripping, wet abrasion or tools with effective extraction. Dry sanding and blow torches are among the methods it warns against. HSE’s lead guidance has the working precautions.

Caustic soda is sodium hydroxide. It is corrosive and can burn on contact. The stripping company should be able to explain its method, rinsing or neutralising, drying and the condition in which the door is returned. UK Health Security Agency gives the substance information.

What I usually prefer

On a painted softwood tenement door, I first check whether it works. Does it close without force? Are the joints sound? Is thick paint the problem, or is moisture involved? An entrance or fire-resisting door may have performance requirements that limit what can be altered.

Where the door is sound, I usually prefer local preparation, filling and repainting. Loose material comes off; well-attached paint stays. Suitable furniture, panelling or finish-grade hardwood can justify a different method, after a small test area.

If a door has already been stripped, let its condition settle before cutting the frame to match it. A joiner can check twist, loose joints and panel movement. The eventual finish should suit the timber and where the door lives.