Keim Optil

Keim Optil is an interior mineral paint system based on a combination of traditional mineral paint and modern silica technology. Sol-silicate mineral paints combine silica particles with the original potassium silicate binder; this enhances many of the performance aspects, and particularly its ability to adhere to non-mineral, i.e. previously painted surfaces. All colours are fade free and the paint is classified as VOC free.

Keim have been producing mineral paints since 1878, utilising potassium silicate and earth oxide pigments to create highly durable and breathable paint systems.  Whilst the original powder paint materials produced in 1878 are still available today, Keim also produce a range of more modern materials which compete with conventional acrylic based paint materials.

Keim Optil has been awarded natureplus certification, ensuring that the product has been stringently assessed from ‘cradle to grave’ in terms of component materials, VOC emissions and its manufacturing process.   This is one of the reasons which makes Keim Optil appeal to the ASBP and makes this product an ideal selection as our featured product of the month.

The benefits

Mineral paints are a ‘breathable’ alternative to conventional acrylic based paint coatings.  Whilst it is seen as the ‘norm’ to pop to your local DIY shop and select your paint based on colour and price, people are becoming more and more aware of the negative impacts which paint can have on both people and buildings.  Many paints have extremely strong chemical smells, which can cause people to feel dizzy and nauseous, and this is because they contain a range of potentially harmful chemicals or volatile organic compounds (VOCs).

The release of these chemicals is commonly called ‘off gassing’ and evidence presented by Sentinel Haus at our Healthy Buildings – the Role of Products on 20th January showed that levels remain high, even after eight weeks. Indeed, it is postulated that off gassing can continue for a number of years, long after the new paint smell has gone.  As well as these potentially harmful effects to those applying the materials and occupying the rooms, conventional paints create a film over the surface which can trap moisture vapour behind them – this is because they have low moisture vapour permeability, also known as breathability. It’s crucial for surfaces to be able to dry out, especially throughout the winter, and it helps to reduce blistering paint and condensation build up which can lead to mould issues.  Drier buildings are also easier to heat and therefore even something like paint choice can help to reduce energy costs.

Keim Optil is chemically solvent and odour free and does not off gas at all. Hannah Maiden, from Keim Mineral Paints, told us ‘the products are lovely to apply, both as a personal user and professional advocator of the materials, it’s so nice not have to worry about what chemicals you are breathing in as you paint, or during my working day, as I am based in a building where the paints are mixed and prepared.’

Keim Optil is designed to be extremely durable; like all mineral paints it is not an acrylic film applied over the surface but the potassium silicate within the paint actually bonds to the mineral surface it is applied to, and creates an extremely strong bond.  The colours are also completely fade free, as they are made using earth oxides and unlike some coatings, the whites never ‘yellow’.

The product

Keim Optil can be applied onto almost all mineral surfaces; including plaster, lime plasterboard, brickwork, concrete and stone work and are available in an extensive range of colours, with bespoke colours also available at no extra cost.

Further information:

To find out more about this product visit or get in touch with the Keim paints sales team at or 01952 231250.

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