Workshop Case Study

Can an old lead-painted door be stripped, left natural and properly sealed?

That was the challenge behind this recent set of doors brought into our Hull workshop.

The customer wanted to get away from layers of old paint and bring the original timber back into view, but there was an additional concern. The doors had previously been coated with lead-containing paint and the customer wanted a finishing system designed to reduce potential exposure to any remaining lead residue as far as practically possible.

Simply stripping the paint wasn't enough for what they wanted.

Instead, we developed a multi-stage process involving professional paint stripping, neutralising, fine sanding, repeated lead testing, a shellac-based sealing coat and two different heavy-duty polyurethane finishes.

The aim

To retain the appearance and character of the original timber while creating a durable, sealed and easily cleaned finished surface, with no indication of accessible lead residue on our final surface test.

Painted timber door before professional paint stripping
The door before stripping, still carrying its previous painted finish.
Stage One

Stripping, neutralising and preparing the original timber

The first stage was our normal professional stripping process to remove the accumulated coatings from the doors.

Older internal doors may have been redecorated numerous times during their life, so what appears to be a single painted surface can actually consist of many separate layers of gloss, undercoat and historic coatings.

Once the paint had been removed, the doors were thoroughly cleaned and neutralised before being allowed to dry sufficiently for the next stage.

We then progressively sanded the timber down to 240 grit.

This refined the surface, removed loose and contaminated surface fibres and gave us a clean, smooth base for the sealing process.

Old timber door stripped of paint and sanded to 240 grit
The door after stripping, neutralising and sanding progressively down to 240 grit.
Lead Testing

Testing the stripped and sanded timber

Because lead exposure was the main concern on this particular job, we didn't want to rely purely on how clean the doors looked.

We tested the surface as the work progressed.

Following stripping and sanding, the doors looked extremely clean to the eye, but the lead test still gave an indication that residual lead was present at the exposed timber surface.

This is a useful reminder that a piece of timber looking completely bare doesn't necessarily mean that every trace of a historic coating has disappeared from the surface fibres.

Lead paint residue test on stripped and sanded timber door
Lead testing after the door had been stripped, neutralised and sanded to 240 grit.
Important: the objective was not to claim that every microscopic trace of lead had somehow been removed from the entire construction of an old door. The objective was to progressively clean the exposed surface and then isolate it beneath a durable finishing system.
Stage Two

Sealing the timber with Zinsser SealCoat

Once we were happy with the preparation, the first barrier coat was applied using Zinsser SealCoat.

This gave us a sealed base over the prepared timber before moving on to the polyurethane system.

It also immediately changed the appearance of the door. The pale freshly sanded timber became warmer and richer and some of the fantastic grain hidden beneath the old paint began to stand out.

Stripped timber door after first coat of Zinsser SealCoat
The first sealing coat applied to the prepared timber.
Testing Again

Monitoring the reduction rather than relying on one final test

We then tested again.

What we wanted to see was a progressive reduction as each stage of preparation and sealing separated the finished surface further from the historic lead-containing coating.

The second test showed that reduction clearly, giving us confidence to continue with the next protective stage.

Second lead residue test after sealing stripped timber
A second lead test carried out after the initial sealing stage.
Stage Three

Polyvine Heavy Duty Polyurethane Satin Clear

The next stage was Polyvine Heavy Duty Polyurethane in Satin Clear.

This added another continuous protective layer over the sealed timber while also giving the doors the kind of durability needed in a busy family home.

Internal doors get a surprising amount of abuse. They are touched repeatedly every day, knocked, wiped down, pushed with dirty hands and exposed to normal household moisture and cleaning.

We therefore wanted the final system to do far more than simply look good when it left the workshop.

Timber door coated with Polyvine Heavy Duty Polyurethane Satin Clear
Polyvine Heavy Duty Polyurethane Satin Clear applied over the sealed timber.
Stage Four

Flatting the cured finish with 800 grit

Once the satin polyurethane had dried sufficiently, the surface was carefully flatted using 800 grit abrasive paper.

This very fine abrasive removes small nibs and imperfections in the coating without aggressively cutting back through the protective layers underneath.

It also provides a beautifully even keyed surface for the final coat.

Polyurethane finish flatted with 800 grit abrasive before final coating
The cured satin polyurethane lightly flatted with 800 grit before the final finish.
Final Stage

Polyvine Heavy Duty Polyurethane Dead Flat

For the final exposed surface we used Polyvine Heavy Duty Polyurethane Dead Flat.

This gave us exactly the appearance we wanted: the protection of a modern hard-wearing coating system without making an old timber door look heavily varnished or glossy.

The low-sheen finish leaves the timber looking remarkably natural while the protective layers underneath provide a surface that can be wiped and maintained much more easily than bare wood.

Finished stripped timber door with Polyvine Dead Flat polyurethane coating
The finished door after its final Polyvine Heavy Duty Polyurethane Dead Flat coat.
The Complete System

Eight stages between the original coating and the finished surface

1

Strip

Remove the old paint and accumulated coatings using the appropriate professional stripping process.

2

Neutralise

Thoroughly clean and neutralise the timber following stripping.

3

Sand to 240 Grit

Progressively refine the exposed timber and remove loose surface fibres.

4

Lead Test

Check the exposed surface and establish the condition before sealing.

5

Zinsser SealCoat

Apply the initial sealing layer over the prepared timber.

6

Satin Polyurethane

Apply Polyvine Heavy Duty Polyurethane Satin Clear for protection and durability.

7

Flat with 800 Grit

Remove nibs and refine the surface ready for its final coat.

8

Dead Flat Finish

Finish with Polyvine Heavy Duty Polyurethane Dead Flat for a natural-looking final surface.

The Result

No indication on the finished surface – and a finish designed to last

At each testing stage we saw a gradual reduction in the indication of lead residue.

Once the complete finishing system had been applied, our final check gave no indication of lead on the finished surface tested.

Just as importantly, the doors looked fantastic.

The stripping process uncovered some wonderful variations in the original timber. Different panels and rails display completely different grain patterns, something that had been hidden beneath paint for years.

Natural Appearance

The dead-flat final coat keeps the timber looking natural rather than heavily varnished.

Sealed Surface

Multiple finishing layers separate the exposed surface from the original historic timber underneath.

Hard Wearing

A heavy-duty polyurethane system makes the doors suitable for years of everyday family use.

After Stripping

Why not simply leave an old stripped door as bare timber?

Freshly stripped and sanded wood can look fantastic, and some customers are tempted to leave it completely untreated.

The problem is that bare timber offers very little protection against dirty hands, moisture, cleaning, staining and normal household wear.

With timber that has previously carried lead-containing coatings, there can also be a strong argument for sealing the prepared surface rather than leaving the original wood continually exposed to handling.

This particular system allowed us to retain virtually all of the visual character of a natural stripped door while creating a much more robust and easily maintained finished surface.

A Note About Lead Testing

What does “no indication” actually mean?

It's important to be precise when talking about lead on historic timber.

Our surface checks during this project were used to monitor the progression of the restoration and finishing process.

The final test giving no indication of lead means that no lead was indicated on the finished surface at the area tested.

It should not be interpreted as laboratory certification that no lead exists anywhere within the original door, joints, mouldings or timber beneath the sealed finish.

Questions

Lead paint and stripped door FAQs

Can old lead-painted doors be stripped back to bare timber?

In many cases, yes. The correct stripping process depends on the construction of the door, the coating present and the condition of the timber. We assess each door before deciding on the appropriate method.

Does stripping remove every trace of lead?

Paint stripping removes the historic coatings, but it is not sensible to claim that every microscopic trace of lead has been removed from every fibre or joint of an old door. Further preparation and a suitable sealed finish can greatly reduce contact with the original surface.

Can you sand and finish doors after stripping?

Yes. As well as paint stripping, we can quote for sanding and suitable finishing systems depending on the timber, intended use and finish required.

Why use a dead-flat polyurethane finish?

A dead-flat polyurethane provides the durability and cleanability of a protective coating while retaining a much more natural, low-sheen appearance than conventional gloss varnish.

Have old painted doors you'd like to bring back to life?

Yorkshire Paint Stripping can strip old doors back to their original timber and can also quote for sanding, preparation and finishing where required.

Send us clear photographs of your doors and let us know the finish you're hoping to achieve.

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