Conservation & Heritage Issue 50 Winter 2025/Spring 2026 - Flipbook - Page 44
Acrylic ‘latex’ paint (plastic dispersion) – this is a fastdrying paint containing pigment suspended in an acrylic
polymer emulsion. A rapid drying time enables a painter to
apply two or three coats in a day and move onto the next
job, this is very advantageous. These paints are often sold as
environmentally friendly because the solvent used is water.
As the paint dries water evaporates and the acrylic polymers
fuse. VOC emissions are low and the painter will suffer no
ill-effects. The downside is that acrylic polymers are derived
from petroleum products, it’s plastic! With Data Sheets
hidden from the public gaze how many people know this?
Acrylic paint consists of polymethyl methacrylate (PMMA)
suspended in water and you need 2 kg of petroleum to make
1 kg of PMMA. Clever marketing by the paint industry
perhaps but since when has using non-renewable fossil fuels
become ‘eco’, ‘green’ or environmentally friendly?
Paint Comparison
For exterior application on new timber
Paint Group
Dry matter
content
Coverage
(m2/litre)
Surface
penetration
Drying time
(top coat)
Longevity
16 hours
± 6 years
4-6 hours
± 4-6 years
24 hours
± 15 years
± 55%
No penetration
≤ 18
(top coat)
Alkyd oil
(artificial oil)
± 40%
No penetration
≤ 12
(top coat)
Acrylic
(plastic)
± 100%
Penetration
Linseed oil
≤ 20
(top coat)
Next Generation Linseed Oil Paint
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We now benefit from the next generations of linseed oil paint
where the ‘nasties’ have been substituted, processes have
been streamlined and the cleaning & sterilising of oil has
been refined, learning lessons from the past 40 or 50 years
of re-production. Distribution is now global and linseed oil
paint continues to see a welcome resurgence.
vulnerable it will be to mould growth. Using the finest
quality oil, pigment and processes means there’s no need
to add solvent, including turpentines, as mentioned above
there are plenty of very harmful ‘natural’ materials. Zinc
Oxide can be added as an option subject to both the project
environment (internal or external) and the client’s wishes.
This offers greater resistance to dirt, pollen, algae and mould
as well as speeding up the drying process.
Remember linseed oil paint ‘dries’ through oxidisation
(this is an exothermic reaction), the dry matter content is
therefore 100%. The quality of the initial cold pressed oil
is still dependant on where it is cultivated. Oilseed flax
grown in northern latitudes (cold & damp climate) is high
in linolenic acid, this contributes to a faster drying time of
the linseed oil and therefore the paint. The proteins have
also been removed from the oil. The higher the protein
content the longer the paint will take to dry and the more
In summary
Modern paint has been unable to successfully replicate the
properties of linseed oil. It does not penetrate, breathe or
remain elastic as linseed oil paint can and has proven to
do so for generations. So, our modern paints don’t last very
long, are rarely ‘green’ and are expensive. We have paid a
high price for paint failure.
Conservation & Heritage Journal
42
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