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What is the difference between acrylic and mineral based silicate masonry paint?

10th May 2019

We’re often asked how our Ecopro Silicate Masonry Paint compares to conventional masonry paint, so we’ve put together this guide highlighting the main differences between these types of masonry paints, along with their advantages and disadvantages.

 

What is masonry paint?

It sounds simple but masonry paint is very different to conventional interior paints. It is a paint finish designed especially for use on exterior walls, including brick, stone, concrete, plaster, lime and cement render, and pebble dash. Due to these being outside, the paint has to perform even better than standard interior paints.

 

Along with adding colour, exterior masonry paint serves to protect a property from weather, pollution and general wear and tear. It should also help to care for the building.

Stone farmhouse painted in Earthborn mineral based Silicate Masonry Paint colour Honeycomb

This stone farmhouse was painted in Earthborn Silicate Masonry Paint colour ‘Honeycomb’ allowing the walls to breathe again

What are the different types of masonry paint on the market?

 

There are three main types of finish suitable for masonry surfaces:

Conventional masonry paints

These are plastic based paints that contain an acrylic binder, with the idea to provide a weather and waterproof coating, preventing water from penetrating through to the wall. Acrylic based masonry paints are perhaps the most common type of masonry paint on the market. It’s ideal if you have a previously painted property that simply needs ‘refreshing’ with a new coat of paint in the short term.

 

Mineral based silicate masonry paints

Silicate masonry paints were first developed in Germany at the turn of the last century by a paint chemist, using very hard materials such as silica (used in glass manufacture) and other water-repellent ingredients. Rather than simply coating the masonry surface, mineral based silicate paints form a physical bond with the masonry substrate. A chemical reaction allows the silicate paint to ‘knit’ into the masonry surface, becoming part of the substrate itself. It is highly breathable, durable and weather resistant.

 

Limewash

Limewash is a traditional masonry coating that has been around for centuries. It is applied in layers which are built up to provide a highly breathable yet protective coating. It is used over traditional building materials such as lime render and is often the preferred option of many heritage and conservation experts. Whilst it is the most authentic finish for many older properties, limewash also requires reapplication every few years and can become dusty and unstable. The task of applying limewash can also be very time consuming and isn’t necessarily a practical option for many homeowners.

 

Acrylic masonry paint vs silicate masonry paint

Acrylic masonry paint is cheap, quick to apply and can go over any previously painted surface. It is ideal for a quick refresh on previously painted, modern properties.

 

Due to its plastic content however, these ‘modern’ masonry paints have a low level of breathability meaning water vapour can’t easily pass through the painted surface. Invariably over time, water will find its way through hairline cracks in the surface where it can become trapped in the walls, eventually causing the paint to flake and bubble.

Earthborn paint case study featuring mineral based silicate masonry paint used on restored windmill

This converted windmill had suffered damp due to non breathable acrylic paint, but was restored appropriately by replacing this with mineral based silicate masonry paint, allowing the walls to breathe again

In some cases, damp that is trapped within the walls can have a detrimental effect on the very fabric of the building. Damp can lead to a whole host of problems for both the building and its occupants. It can cause mortar between the bricks to crumble, bricks to become loose and essentially the building could become unstable in areas! Not to mention the health implications of living in a damp property.

 

Some acrylic masonry paints are marketed as ‘breathable’. Although all paints are breathable to an extent, the level of breathability for paints that contain acrylic is generally quite low. We explain more about breathability levels in paint in this article. If you have been advised to use a highly breathable or micro porous masonry paint for your property, acrylic masonry paints aren’t a long term solution, especially if you have an old property.

 

Earthborn Ecopro Silicate Masonry Paint on the other hand, has a breathability level similar to that of limewash, making it ideal for older properties, conservation projects and lime render. It is regularly used on listed buildings and heritage properties. A chemical reaction with the mineral substrate means that when used together, the paint and primer form part of the surface, so it is highly durable and weather resistant. It won’t flake off and unlike limewash doesn’t need reapplying every few years. Silicate paint is naturally alkaline so resists algae growth and is non-yellowing.

Earthborn Ecopro Silicate Masonry Paint colour Sandstone was used to provide a breathable finish on this medieval property

The external walls of this late medieval hall house have been painted with Earthborn Silicate Masonry Paint in Sandstone to provide a breathable, long lasting alternative to limewash

It has to be used on unpainted masonry surfaces to allow the paint to properly bond to the surface. It’s easy to apply and quick drying, but for more information on how to use the system, head to our product page.

 

If you have an older property, or are working on a building that has suffered with damp caused by the use of unsuitable materials, Earthborn Ecopro Silicate Masonry Paint is ideal. Take a look at our range of 24 standard colours and get your free colour card here.

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