The Development of Paint
There were three main products used in house decoration between 1615 and 1900.
Water Based Paints or Distempers
Oil Based Paints
In the 1890’s Silicate Mineral Paints began to be used on the more important buildings in Europe.
Lime Washes for external and internal use take the form of calcium di-hydroxide in solution, coloured with pigment. This pigment is only dispersed by mixing and therefore results in beautiful shading effects. The lime wash dries and the calcium di-hydroxide turns to calcium carbonate. This provides a sacrificial coating which is built up originally in 3 to 5 coats and then topped up in its maintenance.
Water based paints
Water based paints relied on a white-based pigment (generally crushed chalk) mixed with a solution of an organic binder (normally animal-glue size) in water. When the water evaporated the binder would consolidate the pigment. Distempers of this type were cheap but water-soluble and only suitable for internal use.
Oil Based Paints
Oil Based Paints provided a harder wearing weather/wear resistance surface. In this case the base pigment was usually white lead dispersed in an oil medium (usually linseed oil) which rather than evaporating would harden by polymerisation to provide a tough protective film, binding the pigment particles to themselves and the ground. This process of polymerisation (known colloquially as drying) was speeded up with the addition of a range of metallic compounds known as 'driers'. To adjust the viscosity of the paint, or to lessen the sheen with which it dried, a thinner (generally oil of turpentine could be added).
Varnishes provided transparent finishes by dissolving one or more naturally occurring resins in an organic solvent.
Pigments to provide obliterating power and colour and to provide greater resistance in the case of oil paints was added. The pigments had to be inert, not react with other constituents of the paint or the atmosphere and be light fast. Unfortunately just as today many pigments don't meet all these criteria.
The stock held by one supplier in 1806 gives an indication as to the range of pigments and therefore colours that were available at the end of the eighteenth and beginning of the nineteenth century.
Whiting, Paris White, Satin White, White Lead
Indigo, Blue Verditer, Smalt, Prussian Blue,Verdigris
Green verditer, Scheele's green
Yellow Ochres, Orpiment, Naples Yellow, Patent Yellow, Organic Yellow Red Ochres,
Red Lead, Vermilion, Organic Reds
Umbers, Cologne earth
Lamp black, Ivory black, Blue Black
(the toxic affects of some pigments especially arsenical greens and of white lead were a contemporary cause of concern)
Prior to the mid 18th c Yellow Ochre was one of the most used and stable inorganic pigments which was used in oil and distemper. Although it only ever provided lighter shades. At the beginning of the Victorian period another pigment began to be manufactured at a moderately economical price, Chrome Yellow that provided a brighter yellow.
Organic pigments also provided brighter yellows and included on a base of chalk and aluminium hydroxide berries of Rhamnus, the seeds of a south african plant (bixa orellana), a dye extracted from the roots of berberise, Quercitrin present in the bark of oak trees especially American species, Tumeric – these were all forms of dyestuffs.
A wealth of variety was therefore always there although obviously the more common colours were more easily available. In England for instance Yellow Ochre came (comes) from natural coloured earth like all the ochres. From eg Oxfordshire, where it could be found in a vein between two and seven inches lying at a depth of between seven and thirty feet, The Golden Valley near Bristol, Matlock in Derbyshire and Tavistock in Devon. The colour is due to the presence of various hydrated ferric oxides in earth or clay (umbers contain more manganese oxide and are brown in colour). Examples of these natual paints can be seen in many of the old historic buildings that still exist in the United Kingdom today.
Paint Types Available Today
Silicate paints (from 1890's)
Traditional Natural Emulsions
Traditional Plant Oil Paints
Synthetic Paints (from 1950's)
Lists of Ingredients
Conventional Water-based Emulsion – all petroleum-based, some minerals, some are carcinogenic - acryl-styrene resin (petroleum based), monostyrene (pb), water (natural), 1,2-propaneidole (pb), ethylene glycol (anti-freeze (pb)), disobutyl esters(pb), diurethane (pb), butanole (pb), butoxiethylacetate (pb), phosphoric acid amino salt (mineral), silicon emulsion (pb), white spirit (carcinogen, pb), xylene (c, pb), silicone (pb), unspecified solvents, oxialkylized compound (pb), azo-pigment (pb), titanium dioxide (m), calcium carbonate (m), n-methylole-chloracetamide (pb), Isothiazolinone compound (pb), Formaldehyde (pb).
Eco-emulsion – all from minerals or renewable materials of plant or animal origin - tap water,titanium dioxide, aluminium silicate, diatomaceous earth, zinc white, beech cellulose, talcum mica,dehydrated castor oil, dammar resin, colophium glycerol esters, refined linseed oil, beeswax soap, shellac, lecithin, methylcellulose, boric salts, turkey red oil, milk casein, lavender oil, thyme oil.
Simple traditional paints and silicate mineral paints ensure that the surfaces of historic walls can breathe out water vapour.
Choosing a Wall Paint
Maintain moisture control – particularly important for solid wall construction – avoid blistering;
Conditions for Applying Paints
Make sure conditions are right not too cold (minimum temperature is usually 5ºc – applies to surface as well as air), not too hot (maximum temperature is 30ºc for surface or air).
Avoid direct sunlight.
Follow manufacturer's instructions
Damp – important to maintain/promote moisture control and avoid paints such as casein that can grow mould (protein);
Intended Room Usage – Level of Durability – help you to decide on whether or not your surface needs to be wipeable etc
Understand your Background
e.g. Stone, brick etc, Lime Plasters/Renders, Old Paint eg Limewashes, Clay
e.g. Cement, Gypsum Plaster, Plasterboard, Wallpaper, Old Paint
A Technical Introduction to Silicate Paints:Composition and Building Physics
Binder = Potassium silicate - water glass
Thinners = Potassium silicate - water glass & water
Pigments = Mineral
Driers = None
Additives = acrylic resin as an additive stabilizer, not as binding agent & Thickening Agent
The Different Types of Silicate paints/Mineral paints
Silicate paint with two components, silicification active
Organo-silicate paint one component, ready-to use silicification, active or passive
Sol-silicate paint (silica sol and potassium silicate)
Dispersion in acrylic binder
Dispersion in the silicone resin
Pure Silicate Paint or two-component Mineral Paint (DIN 18363)
The mineral paints must be composed of liquid glass, stable potassium silicate and pigments and are not allowed to contain organic substances
Fixative (liquid glass) + Mixture of pigments and fillers in powder form in bags.
Mineral Paint two component/Organo-Silicate Paint (DIN 18363)
Organo-silicate paints must be composed of liquid glass, pigments stable potassium silicate, hydrophobic additives and are permitted to contain organic substances max 5% Eg BEECK Beckosil, BEECK Insil, BEECK Renosil DIN 18363 Fixative (liquid glass) + Filling pigments + repellent + thickener stabilizer (Acryl) Organic content approx 3.5% stabilizer (Acryl) Organic content approx. 3.5% Sol
The silica sol is a derivative of liquid glass. This liquid glass reduces alkalinity. Following the reduction in alkalinity the binding power and silicification with the support are reduced as well. The paintings Sol-Silicates then need the tackiness of acrylic components to adhere to the mineral support. The Sol-silicates paints are then always passive, i.e. not silicification active.
Silicate paint active or passive?
Active silicate paints are resistant to paint stripping they are actively inseparable from the substrate
Paint Stripping Test
99% of one component mineral paints can be removed by paint strippers for instance Dulux Weather Shield. This is because all these paints are essentially emulsions bound by acrylics.
Active silicate paints however adhere to the wall only by the formation of a vapour permeable mineral bond and not by the formation of a plastic film on thesurface. These paints do not contain synthetic binders
Why does the silicate paint need to be Active?
If the nature of the walls surface is filled with the activity of the movement of water vapour in and out of itself then the paint covering has also got to be active and form part of the background mineral plaster /render / brick/ stone.
Passive internal or external emulsion type paints are only suitable for passive none breathing backgrounds.
The Advantages of Active Silicate Paints
very resistant against bad weather, very durable
absolutely resistant against UV rays
no preservative necessary
they work with the physics of the building (diffusion/condensation/mould)
simple renovation without paint stripping
Salts in the background
If salts are in the background then the application of active silicate paints results in the formation of silicate salts and not the formation of a protective mineral paint.
If salts are in the background but no longer moving then they can be prevented from penetrating the paint system by the application of Silane Primer. All salt movement must be stopped.
Active silicate paints do not hide the Background
This paint is not forming a film and hiding the background
Active silicate paints form part of the active substrate and therefore will show areas of higher humidity. Although this can be equalised out using quartz filler.
Preparation of the background
To work active silicate paints need to be applied to an active quartz based background such as a limestone, lime or a cement render. If they can not be applied to an appropriate background then one has to be created. (eg Gypsum/Insil primer or Bonding Coat)
The active silicate paints need to be carried into the background by water. For the paint to penetrate the background it needs to be free of organic growth (apply water based biocide) and not have a hard sinterskin (apply etching fluid). Excessive suction on the background needs to be tempered by first applying pure waterglass in solution (fixative)
Do not paint with a water based paint when rain is expected.
Always keep a wet edge and do not overlap areas.
Emulsion based paints stay sticky for 2 years and attract dust and grime. After 5 years they begin to crack and peel.
Active silicate paints are self cleaning and their initial alkalinity reduces the potential for organic growth. They have a 15 year guaranteed life. This can be extended with silicate hydrophobic coating.
The Need for Timber to Flex
Synthetic Paints do not flex with the timber
Paints & The Environment
the manufacture of synthetic paints and solvents puts nearly as much pollution into the environment as the fumes from motor car exhausts – Chemicals in Paint, Hartwin Busch.
the production of 1 tonne of acrylic paint can produce up to 30 tonnes of waste of mostly low biodegradeability.
Painters/Decorators have an increased risk of contracting serious diseases – the WHO organisation class painting as a carcinogenic profession
What is an Environmental Paint?
made from renewable, natural raw materials e.g. oils from plants;
no human health hazard;
avoid petrochemicals and exclude toxic products and those materials that have toxic by-product during manufacture;
are designed to be biodegradable.
Internal Environment & Health
"…it is apparent that our homes are cosier, but potentially far less healthy – especially when cooking smells,water vapour from bathing and laundry etc…are all brought into the picture. As a result we are creating ideal conditions, not so much for people, as for the fungal moulds, bacteria and dust mites which thrive in warm, humid conditions. A recent study has found that that allergen levels in super - insulated homes is 200 per cent higher than in 'ordinary' homes, whilst the American college of Allergies goes so far as to assert that 50% of all illness is aggravated or caused by polluted indoor air.Dustmite droppings have been identified as a primary cause of asthma." Sustain, Volume 5, Issue 2.
Walkley Lane, Heckmondwike, West Yorkshire, WF16 0PG