Earthborn Silicate Masonry Paint - Which Primer do you need and other FAQs

The Silicate Masonry Paint from Earthborn, with a lifespan of up to 15 years, is a great alternative to traditional lime based or conventional masonry paints.

Originally formulated as highly breathable exterior paint as an alternative to traditional lime-based paints. It can now also be used over conventional paints. However, the key to where you can use the Silicate Masonry Paint lies in which Primer you use as an undercoat. 

For Silicate Masonry Paint to work effectively it must be used with either Earthborn’s Silicate Primer or Bonding Primer. 

We have put together this handy guide to which Primer to use with the Earthborn Silicate Masonry Paint. 

Picture: Left to Right, Bonding Primer, Silicate Masonry Paint, Silicate Primer. Note: This range is transitioning from plastic containers to metal tins.

Silicate Primer

Use the  Silicate Primer from Earthborn over bare porous unpainted masonry substrates such as lime plaster, stone, pebbledash & concrete. When used with Earthborn's Silicate Masonry Paint it will create a highly breathable and permanent chemical bond. It creates a water and weather-resistant barrier while remaining water vapour permeable which enables the building to breathe. 

Note: Some clay surfaces may require special treatment.

Bonding Primer

Use the  Bonding Primer from Earthborn over previously painted sound conventional masonry substrates. This includes surfaces painted with “plastic” or acrylic paints. When used with Silicate Masonry Paint it will create a strong mechanical bond. The surfaces painted with the Bonding Primer will not be breathable. 

Once you know which Primer you need, the application of Earthborn Masonry Paint system is very easy in three coats as follows:

Note: Don’t apply the paint in temperatures below 8°C or if low temperatures are expected within 24 hours of application, and avoid painting if the substrate temperature is below 8°C. Don’t apply the paint in direct sunlight.

FAQs 

Do I need the Silicate Primer if I am re-painting a wall already painted with Earthborn Silicate Paint?

Yes, if the walls have definitely been painted with the Earthborn Silicate Paint, you can overpaint by applying a diluted coat of 80% Silicate Masonry Paint to 20% Silicate Masonry Primer, followed by a full coat of undiluted paint.

Can I use Earthborn Silicate Masonry Paint over Limewashed walls?

Yes, follow the coats system for the Silicate Primer and Silicate Masonry Paint. However, as the Primer forms a bond with the substrate and limewash is not always a stable surface, we recommend that you remove as much as possible prior to overpainting.

I don’t know what paint has been used on my property, what would you recommend?

It can be difficult to tell what a surface has been painted with. If you really don’t know what paint has been used on your outside walls and suspect you need a breathable finish (because you have an older property or eco-home), we recommend using  Graphenstone GrafClean Exterior Wall Paint. It has the benefit of being able to be painted over most* sound surfaces and also being highly breathable and hardwearing. Painting a wall or patch with a tester pot is recommended before going ahead with the whole job. 

*Substrates must be resistant to high alkalinity. If in doubt apply to a test area first.

Another option is Keim Soldalit Exterior Silicate Paint or Keim Solalit ME Exterior Silicate Paint (may require a first coat of Soldalit Fixative - see product web pages for details). Keim Soldalit is a great solution for consolidating walls made up of multiple finishes, forming a chemical bond with mineral substrates and a mechanical bond to existing coatings. It is also a breathable paint system, hardwearing and water repellent and highly water vapour permeable.

I’ve tried removing the previous masonry paint so the wall can breathe, but there are patches that I can’t get off. What should I do? 

Your main priority is keeping the breathability. The best way to address this is to spot prime the patches where the previous paint cannot be removed with Bonding Primer (please be aware these patches will not be breathable). Then prime the rest of the unpainted area with Silicate Primer. For the second coat apply a mixture of 20% Silicate Primer and 80% Silicate Masonry Paint over the whole area including the areas that have been spot primed. Then finish with a final coat of Silicate Masonry Paint.

Alternatively, you could use  Graphenstone GrafClean External Wall Paint over the whole area after removing as much of the previous paint as practically possible (instead of the Earthborn paints/primers). GrafClean has the benefit of being able to be painted over most* sound surfaces and also being highly breathable and hardwearing. Painting a wall or patch with a tester pot is recommended before going ahead with the whole job.

*Substrates must be resistant to high alkalinity. If in doubt apply to a test area first.

Or you could use Keim Soldalit Exterior Silicate Paint or Keim Solalit ME Exterior Silicate Paint (may require a first coat of Soldalit Fixative - see product web pages for details). Keim Soldalit is a great solution for consolidating walls made up of multiple finishes, forming a chemical bond with mineral substrates and a mechanical bond to existing coatings. It is also a breathable paint system, hardwearing and water repellent and highly water vapour permeable.

If I paint a “breathable” paint over an unknown paint will the wall become breathable?

Not if the paint underneath or construction method of the wall is impermeable. The wall is only as breathable as the least breathable finish that has been applied or what the wall is made from. You cannot make it breathable just by applying a breathable paint.

If the wall has been painted with a non-breathable paint, a breathable paint over the top will not make the wall breathable. It’s a bit like someone wearing a cotton shirt over a plastic bag.

If the wall needs to be breathable (because it’s an older building or some types of eco-builds). You will need to remove the non-breathable surfaces (as far as practicable) prior to painting to make the wall breathable.

Can I use an airless spray gun to apply Earthborn’s Silicate Paints and Primers?

The Bonding Primer is suitable for spray application and can be thinned with 5% water if required.

The Silicate Primer is not suitable or spraying as it would result in the Primer becoming airborne and potentially etch into any metal or glass in the area. It could cause irreversible damage.

The Silicate Masonry Paint is suitable for spray application as follows: 

• Tip Size: 419
• Pressure (psi): 2800
• Gun Filter: 60 mesh
• Thinning: Up to 10% with Silicate Primer
• Recommended Pump: Titan 840i (or equivalent).

How do I paint Cob or Clay walls with Silicate Masonry Paint?

Cob and clay are soft substances that shouldn’t be directly painted with Silicate Masonry Paint because it won’t bond correctly. However, cob or clay walls that have been coated in lime render first can be painted with a first coat of Silicate Primer, second coat primer and paint mix, final coat paint (see steps for Silicate Primer above for mixes/drying times etc).

My question is not answered here

If you have any other questions about breathable paints for external walls or the Earthborn Silicate Masonry Paint System, please do not hesitate to  contact our knowledgeable team.