Professional Guide

Best Exterior Wood Paint for Sash Windows: 2025 Expert Review

DR Joinery

Expert Joiner & Restoration Specialist

Published 12 December 2025

Painting sash windows is perhaps one of the trickiest jobs for a homeowner. Unlike a standard casement window, a sash window has sliding parts that can easily become painted shut if the wrong product is used or if patience isn't applied. I've spent too many hours unsticking windows that were painted with thick, unsuitable glam paints.

Living and working in York, we deal with damp, cold winters and old Victorian timber that moves with the seasons. The paint you choose needs to be flexible enough to move with the wood, breathable to let moisture escape, and durable enough to withstand the northern weather.

In this review, I'll analyse two specific exterior paints I've looked at recently: a budget-friendly satin that's widely available, and a premium professional-grade option. I'll explain which one is right for your restoration project.

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Specs vs. The Real World

The Spec: "Dry Time & Blocking"

The Theory

"Most modern paints claim to be 'touch dry' in 1-2 hours."

The Reality

Whilst the surface may be dry, the paint film stays soft for days. If you close your sashes fully too soon, they will fuse together. Always leave them slightly open or run a wax candle along the meeting edges before closing.

The Spec: "No Primer Required"

The Theory

"Many paints claim to be self-priming to save time."

The Reality

On fresh Accoya or sound Oak, this is fine. On old, restored Victorian softwood that has been stripped back, I always recommend a dedicated microporous primer to spot-prime knots and resinous areas first.

My Top 3 Recommendations

Three options to cover different needs and budgets

Johnstone's - Quick Dry Satin - Pale Cream - Satin Finish - Exterior Wood & Metal

Budget Pick

Johnstone's

Johnstone's is a staple on many job sites for a reason: it is reliable and affordable. This water-based satin finish is particularly good for sash windows because it dries quickly, reducing the 'blocking' risk where windows stick together. The pale cream colour is a classic choice for heritage properties avoiding brilliant white.

Price£15.82 (£21.09 / l) (at time of writing)

BrandJohnstone's

FinishSatin (Mid Sheen)

TypeWater-based

The Good

Excellent price point for decent quality
Water-based formula is low odour and quick drying
Satin finish hides minor imperfections better than gloss

The Bad

Opacity can be lower on pale colours; requires good undercoating
6-year life is optimistic in exposed northern locations

Installer Tip:

Because this is water-based, it raises the grain slightly on bare wood. After your first coat, give it a very light sand with 240-grit paper to de-nib the surface before applying the top coat. This ensures the sliding action remains smooth.

Priced at £15.82 at the time of writing

Check Price on Amazon

Paintnuts Wood Window & Door Paint - RAL-8016 - MAHOGANY BROWN Satin 250ml Tin

Quality Pick

Paintnuts

This is a serious product for when the finish absolutely matters. Whilst expensive per litre, this professional-grade paint offers superior UV resistance and requires no separate primer, saving labour time. The Mahogany Brown tone is excellent for period properties looking to restore a darker, traditional timber aesthetic.

Price£17.99 (£71.96 / l) (at time of writing)

BrandPaintnuts

CoverageHigh opacity

FeaturesNo primer needed, UV resistant

The Good

Professional grade adhesion without primer
Excellent UV resistance prevents fading on south-facing windows
Tough, extensive durability suited to front elevations

The Bad

Very expensive per litre compared to standard trade paints
Small 250ml tin is only suitable for small jobs or touch-ups

Installer Tip:

Given the small tin size and high cost, I recommend using this specifically for the sash sills (the bottom horizontal part). The sill takes the brunt of the weather and standing water. A high-grade, UV-resistant paint like this on the sill can extend the window's life significantly, even if you use a standard paint for the internal frame.

Priced at £17.99 at the time of writing

Check Price on Amazon

Frequently Asked Questions

Should I use gloss or satin/eggshell for sash windows?

Historically, gloss was used for durability, but modern satin or eggshell finishes are now preferred by most joiners in York. A satin finish is more forgiving on older, uneven timber surfaces and allows the wood to breathe better than thick, high-gloss oils. It also looks more sympathetic on heritage properties.

How do I stop my sash windows sticking after painting?

This is the most common issue we see. First, paint the meeting rails and let them dry fully before closing the window. Second, apply a light coat of candle wax or specialized joinery wax to the running stiles once the paint is cured. Third, operate the window up and down a few times during the drying week to break any seals forming.

Is water-based or oil-based paint better for exterior wood?

For years, I swore by oil-based paints. However, modern water-based acrylics (like the Johnstone's reviewed above) are now superior for sash windows. They stay flexible, meaning they don't crack when the wood expands in winter. They also dry much faster, allowing you to close the house up securely at the end of the day.

Do I need to strip old paint off before repainting?

If the existing paint is sound, a simple sand and clean is enough. However, sash windows often have 100 years of paint layers, clogging the detail and the sliding mechanism. In restoration projects, we often strip the sashes back to bare wood to restore the sharp profile and ensure smooth operation.

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