Silicone Paint vs Acrylic Masonry Paint UK: What the Data Sheets Declare

Two masonry paints, one wall, and a choice usually settled by a slogan rather than a document. The Renders World silicone masonry paints collection holds the silicone half of that choice, and everything below is rebuilt from two manufacturer sheets read in full: the Atlas Salta technical data sheet dated 6 May 2024, and the Ceresit CT 42 acrylic facade paint sheet.

What those documents show is not the familiar split. The classes supposed to divide the two technologies come back identical, which moves the decision onto substrate age, working temperature, consumption and colour policy. For the same argument one layer down, at render rather than paint level, the silicone render and acrylic render comparison owns that pillar question.

How to Choose Between Silicone and Acrylic Masonry Paint on Declared Values

Silicone paint vs acrylic UK choices turn on declared values, and both the Atlas Salta and Ceresit CT 42 sheets declare W3 water permeability at under 0.1 kg/m²·h⁰·⁵, so exposure alone cannot separate them. Vapour movement lands in the same place: both give an equivalent air layer Sd of 0.14 m to 1.4 m. Two documents, one answer — so the specification is decided on the lines underneath.

Those lines are where the two paints genuinely part company, and each one changes a programme rather than a brochure.

• Substrate age the sheet accepts: Atlas Salta paints thin-coat mineral render from five days. CT 42 asks seven days on thin-layer mineral render, fourteen on lime-cement plaster and twenty-eight on concrete, and states it should not go onto substrates of raised alkalinity such as fresh mineral render. On a new-build programme that is two days and one stage.
• Working window: Salta runs +5 °C to +30 °C, CT 42 +5 °C to +25 °C, both below 80% humidity — the useful gap sits at the top of a July elevation rather than the bottom.
• Cold-weather route: adding ATLAS ESKIMO takes Salta down to 0 °C and up to around 80% humidity. The CT 42 sheet names no equivalent, which shortens the season it plans into.
• Consumption, read at matching scope: Salta gives 0.25 l/m² per coat on thin-coat mineral render; CT 42 gives approximately 0.3 l/m² for two coats. Quoted the same way that is 0.5 against 0.3 l/m², and the acrylic is the leaner of the two.
• Colour policy: Salta publishes 406 SAH shades, six of them whites, with no restriction printed. CT 42 holds dark colours to small areas such as architectural details, so a deep full-elevation colour is a decision the Salta sheet supports and the CT 42 sheet does not.

Where Atlas Salta Silicone Paint Earns Its Place on a UK Wall

Atlas Salta is a polymer-dispersion facade paint with selected fillers and pigments, and the sheet describes a compact, smooth film that dirt particles and fungal spores lose contact with easily, so rain and wind carry them off naturally. That self-cleaning behaviour is stated as a property of the surface itself rather than as an additive that depletes.

The supporting figures are specific and worth reading exactly. Water permeability is W3, low, under 0.1 kg/m²·h⁰·⁵. Vapour transmission is V2, medium, between 15 and 150 g/m²·d — medium is the sheet's own word, so a wall that must stay as vapour-open as possible is worth specifying deliberately. Hiding power is declared as class 2 at an 8 m² yield, which makes it a sound two-coat paint and sets the order quantity accordingly.

• Coverage by substrate: 0.25 l/m² per coat on thin-coat mineral render (about 4.0 m² per litre), 0.22 l/m² on dispersion renders (5.0 m²), 0.15 l/m² on smooth plaster (7.0–8.0 m²). Texture sets the quantity, not the brand.
• No primer stage: the sheet states priming is not required because the first coat primes the substrate, thinned by 5% — 0.5 litres of clean water per 10-litre bucket — with the final coat and all spray work undiluted.
• Drying and recoat: 2 to 6 hours to dry and about 6 hours to the next coat at 20 °C and 50% humidity, so both coats fit inside one long day.
• Two bases, one declared performance: the values above apply to Atlas Salta base white 10 L and Atlas Salta base grey 10 L alike, so the base follows the depth of the SAH shade.
• Old and absorbent walls: allow at least 48 hours of dry weather after rain before painting an old render, and even out a chalky or patched surface first with one of the exterior render primers stocked here.

One scope line matters more than any figure above. Salta is named as a component of assessed insulation systems — ATLAS ETA-06/0081, ATLAS ROKER ETA-06/0173, ATLAS GRAWIS ETA-16/0933 and ATLAS XPS ETA-07/0316, with several ITB national assessments alongside. Those describe assemblies, and the sheet publishes no reaction-to-fire class for the paint on its own.

Where Acrylic Masonry Paint Fits, Read From the Ceresit CT 42 Sheet

Ceresit CT 42 is a dispersion of acrylic resins with mineral fillers and pigments, supplied in 15-litre containers, and it is not stocked at Renders World — it stands here as the documented acrylic reference rather than as something to order. Reading it properly is what keeps the comparison honest, because it declines to behave the way acrylic is usually described.

Its EN 1062-1 line is explicit: cat. W3 water absorption at w ≤ 0.1 kg/m²·h⁰·⁵ and cat. V2 vapour permeability at 0.14 ≤ Sd ≤ 1.4 m. The film is thinner, E2 at 50 to 100 µm against Salta's E3 at 100 to 200, and it is the acrylic rather than the silicone that carries a declared abrasion figure.

• Biological protection is declared, not absent: the sheet describes a BioProtect formula whose biocide capsules release under control for a long-lasting effect — the reverse of the usual claim that acrylic leans on additives that soon wash out.
• Abrasion is measured: 20,000 scrub cycles to DIN 53778-2, with facades washable by low-pressure equipment. No comparable figure appears on the Salta sheet.
• Fire is stated at system scope: B-s1, d0 within the named Ceresit Ceretherm systems the sheet lists. That is an assembly figure, never a property of the tin, and the same reading applies to the BBA and Irish Agrément numbers listed as documents of reference.
• Where it is at its best: sound, mature, previously coated mineral surfaces in pale shades, painted in a settled window — resistance to rain after about 12 hours, 4 to 6 hour breaks between coats, no more than 10% added water.

Brand scope cuts both ways in this category, and a class read from one manufacturer's sheet never transfers to another's. The Atlas and Ceresit certificate scope comparison applies the same discipline on the render side.

The Two Sheets Side by Side — Classes, Consumption and Conditions

Each column is transcribed from that product's own sheet at that sheet's scope. The Ceresit sheet names EN 1062-1 as the standard behind the class letters; the Atlas sheet prints the same letters without naming a standard, which is a documentation difference rather than a performance one.

What Silicone Masonry Paint Costs per Square Metre Today

Both bases read £57.50 per 10-litre bucket at the Renders World product endpoints in August 2026, with no VAT figure displayed alongside them, so the base is currently a colour decision rather than a budget one. Everything below is material only — no labour rate was read this session, and a painted wall is never one number.

• One bucket, one coat: 10 l ÷ 0.25 l/m² = 40 m² on thin-coat mineral render.
• One bucket, two coats: 0.25 l/m² × 2 = 0.5 l/m²; 10 l ÷ 0.5 l/m² = 20 m².
• Material cost: £57.50 ÷ 20 m² = £2.88/m² for a two-coat finish at that consumption.
• A 100 m² elevation: 100 m² × 0.5 l/m² = 50 l, so five buckets at £57.50 = £287.50 before cutting-in.
• Smoother substrate: at 0.15 l/m² per coat, the same wall takes 100 × 0.3 = 30 l — three buckets, £172.50.

Texture moves that figure by two thirds, which is why an order sized on the rougher consumption arrives right first time. No acrylic price is quoted here because no acrylic paint is stocked, so the two technologies are compared on their sheets rather than on a till.

Which Masonry Paint to Choose for Your Wall

Four lines separate these documents, and a silicone paint vs acrylic UK specification comes down to how fresh the render is, how hot or cold the working weeks will be, how dark the colour is, and how much of the elevation it covers. Answer those and the paint chooses itself.

Silicone earns its place on render five days old that needs painting inside the programme, on a deep SAH shade across a whole facade, on shoulder-season work that needs the route down to 0 °C, and wherever removing the primer stage saves a visit. The heritage and conservation guidance covers the breathability question on older masonry in more depth.

Acrylic earns its place on a mature, sound, previously coated mineral wall in a pale shade, painted in a settled window, where the lower two-coat consumption and the declared scrub resistance are worth having. It is a solid, documented refresh — just one with a narrower envelope.

Key Takeaway: These two sheets declare the same W3 water class and the same Sd 0.14–1.4 m band, so breathability does not decide between them. Choose silicone for fresh render, deep colours and cold-weather programmes; choose acrylic for mature, pale, well-timed refreshes.

For the exposure question at render level, the UK climate performance ranking works through the same sheets. When the colour and the base are settled, the Renders World Atlas Salta silicone paint range holds both tinting bases, and the wider rendering materials catalogue carries the primers and preparation products the same wall needs.

Written by Mariusz Saja. Technically reviewed by Rafał Wyrzykowski. Last reviewed Aug 2026.

FAQ — Silicone and Acrylic Masonry Paint

How much silicone masonry paint does a 100 m² wall take?

At the sheet's 0.25 l/m² per coat on thin-coat mineral render, two coats need 0.5 l/m²: 100 × 0.5 = 50 litres, so five 10-litre buckets, or six with cutting-in allowed for. On smooth plaster at 0.15 l/m² the same wall takes 30 litres. A trial area remains the accurate way to confirm consumption on textured work, and Atlas Salta base white is the bucket for pale schemes.

Is silicone masonry paint actually more breathable than acrylic?

Not between these two products. Atlas Salta declares V2 with an Sd of 0.14 to 1.4 m per coat, and Ceresit CT 42 declares cat. V2 across the identical 0.14 to 1.4 m band. Compare the Sd figures product by product rather than the binder name, because the ranking can invert across brands and the category word on a label carries no threshold of its own.

Can Atlas Salta go over a wall that is already painted?

Existing paint coatings appear among the substrates on the Salta sheet, and sound, well-bonded film is a workable base once chalking, flaking and growth are removed and small defects are filled. Some coated substrates are routed to other Salta variants, and that row-by-row mapping could not be resolved unambiguously from the fetched sheet, so send the substrate description through with the colour code and have the variant confirmed before tinting.

How soon after rendering can it be painted, and how cold can it go?

Five days on thin-coat mineral renders, seven on dispersion renders and two to four weeks on traditional mineral plasters. Standard application runs +5 °C to +30 °C below 80% humidity; ATLAS ESKIMO extends that to above 0 °C and around 80% humidity. In unfavourable weather the sheet allows a third coat to even the surface, so a marginal week still finishes cleanly.

Which of the two is the lower-VOC choice?

Only one of them publishes a figure. The Salta sheet declares a maximum VOC content of 39.9 g/l in category A/c/FW, against a permitted 40 g/l. The CT 42 sheet states no VOC content, so no comparison is available on that property and none is offered here — ask the manufacturer for the safety data sheet if the number is needed for a specification.