ATLAS GEMINI RS RENDER GREY BASE 25kg

Atlas Gemini RS Render Grey 25kg is the grey tinting base of a fibre-reinforced silicone render, and it exists for the darker half of the palette. A deep shade is the one decision on a thin-coat facade that reaches backwards into the build-up, because the reinforced layer underneath has to suit the colour going on top of it.

Atlas Gemini RS Render Grey 25kg on a Deep-Shade Specification

Gemini RS is a ready-mixed thin-coat silicone render, tinted to order and laid at grain thickness by hand or through a machine. The grey base is the route trade buyers take to mid-tone and deep colours, and Renders World stocks it in the silicone render range alongside the white base.

• Binder and reinforcement: silicone, reinforced with fibres under the name ATLAS 3D-flex.
• Texture: baranek — the lambskin finish — at grain up to 1.5 mm.
• Colour: 406 SAH shades, tinted in house on our own mixer.

Two things about this render are worth settling before a shade is signed off. The first is that a deep colour carries a documented condition on the layer beneath it, set out in the next section. The second is a matter of identity: Gemini RS is not Atlas Silicone Render. They come from the same manufacturer and sit in the same aisle, but they are separate lines with separate documentation, and Gemini RS is not among the finishes covered by BBA Agrément Certificate 13/5018.

How a Deep Shade Changes the Build-Up

Atlas ties intensive colours to the light reflection coefficient of the finished surface, and the rule has two branches. Above HBW 15, an intensive shade is permitted where the reinforced layer is built on one of three named Atlas adhesives. Below that reflectance, an intensive shade is limited to a share of the elevation.

Reflectance of the chosen shade	What the declaration permits	What has to be on the specification
HBW above 15	Intensive colours across the elevation	Reinforced layer on STOPTER K-50, K-20 or GRAWIS U
HBW above 15, GRAWIS U route	Same, with a thicker reinforced layer	At least 5 mm, Atlas 150 mesh doubled
HBW at or below 15	Intensive colours on a maximum of 10 % of the elevation	Treat the dark shade as an accent

 

That is the whole reason the grey base is a specification decision and not a shopping one. Pick the shade first, take its HBW from the Atlas render colour charts and sample books, and only then fix the basecoat, so a deep shade is signed off on a build-up chosen to carry it. The guidance on dark render shades and solar exposure covers what else changes as a facade darkens.

One property of Gemini RS works directly against the heat a dark surface collects. MIRROR EFFECT is credited with a high light reflection coefficient, a lower surface temperature on the render itself, and protection of the polymer resins and pigments against UV — the three things that decide whether a deep colour still looks deliberate after five summers.

The Exposures Gemini RS Is Named For

Most technical data is written in generalities. This one names its conditions, and the list reads like a survey of the elevations that ask the most of a finish.

• Impact at ground level — playground surrounds, walk-through and drive-through gateways, vehicle parking zones. Resistance to mechanical damage is one of the two properties Atlas puts Gemini RS forward for.
• Soiling — exploitation factors, heavy dust and industrial pollution: urban and built-up areas, industrial, investment and economic zones.
• Damp and shade — wetlands and ground near water, close proximity to woodland and green areas, and elevations that stay in shadow. Rural and farm sites are on the list too.

Three mechanisms of Gemini RS answer that list, and they are worth knowing separately because they do different jobs. CLEAN TECHNOLOGY is hydrophobicity through the structure and on the surface: rainwater and surface dust are kept from penetrating, dirt has nothing to bind to, and rain washes it off rather than driving it in. Gemini RS is also credited with drying very fast once rain stops, which is what removes the window in which mould, algae and lichen would otherwise establish.

BIOSEC works chemically rather than physically. ATLAS CAPS releases biologically active agents slowly across the service life of the coat and quickly during heavy rainfall, so the protection is at its strongest exactly when a wet, shaded wall needs it. And MIRROR EFFECT adds a third route: photocatalytic self-cleaning is initiated at the surface, on top of the reflectance and UV protection described above. On a north-facing elevation under trees, those three together are the argument for Gemini RS; where the exposure is milder, our acrylic and silicone-silicate ranges cover the same job.

Scope is stated as plainly as the exposures. An EPS ETICS elevation, a single-leaf wall elevation and an interior wall are all in scope; eleven building types are listed and every one of them is in scope, heritage buildings and passive and low-energy construction included. Two cases fall outside Gemini RS: a mineral wool build-up takes SYSTEM ATLAS ROKER instead, and a ceiling soffit takes ATLAS ROKER G. Both are substitutions to settle before the boards are ordered, not after.

What Is Declared for Gemini RS

The values below belong to Gemini RS itself. They travel with it whichever system it goes into, and they are identical for both tinting bases because the declaration covers ATLAS GEMINI RS as a product.

Property	Declared value	Scope
Water vapour permeability	V2	Product, EN 15824
Water absorption	W2	Product, EN 15824
Diffusion resistance	0.14 ≤ Sd < 1.4 m	Product
Adhesion	0.35 MPa	Product
Reaction to fire	none declared	Product
Density of the ready product	approx. 1.9 g/cm³	Product
Reaction, pH	8	Product
Grain and texture	up to 1.5 mm, baranek	Product
Colours	406 SAH shades	Product
Consumption, hand	from 2.3 kg/m²	Product, even substrates
Consumption, machine	from 1.9 kg/m²	Product, even substrates
Working temperature	+5 °C to +30 °C	Product
Relative humidity	below 80 %	Product
Surface dry / dry	approx. 15 min / approx. 24 h	Product, at 20 °C and 50 % RH
Pack size	25 kg plastic bucket	Product
Shelf life	12 months from production	Product
Standard and DoP	PN-EN 15824:2017-07 · DoP 280/CPR	Product
Intended use, outside	walls, ceilings and columns	Product, from the DoP
Intended use, inside	walls, ceilings, columns, partitions	Product, from the DoP

 

System credentials are a separate matter, and mixing the two is how a product ends up described as certified when it was the wall build-up that was assessed. Gemini RS is named in two Polish national technical assessments; it is not named in the British certificate that covers the Atlas/Aval EPS system.

Assembly	Assessment	Scope
ATLAS GRIP	ICiMB-KOT 2022/0180, issue 1	System, Polish national assessment
ATLAS ETICS	ITB-KOT-2020/1616, issue 3	System, Polish national assessment
BBA Agrément 13/5018	Gemini RS is not one of the finishes it covers	System, and not this render

 

Grey Base or White Base — What Decides It

Gemini RS is stocked here in a grey base and a white base. The split is a tinting decision made in our mixing room: a mid-tone or deep SAH shade reaches its intended depth from grey, while whites, creams and light pastels reach theirs from white.

Tinting base	Chosen for	What the documentation states
Grey base	Mid-tone and deep SAH shades	No separate declaration for a base
White base	Whites, creams, light pastels	No separate declaration for a base

 

The published declarations cover ATLAS GEMINI RS as a product and name no tinting base anywhere. So the honest statement is this: which base you take is our tinting practice and nothing more, and no document sets one base above the other on performance. Choose the base that reaches your shade in the fewest passes, take the shade itself from the fan deck before anything is tinted, and expect any bespoke reference to be confirmed against a tinted sample.

How to Apply Gemini RS Grey — Preparation, Stirring, Texturing

1. Prepare the substrate so it is stable, seasoned, dry, even and clean. Unevenness and voids are filled with ZW 330, ZAPRAWA TYNKARSKA or a reinforcing-layer adhesive; where biological growth is present it is removed with Atlas Mykos Plus biocidal wash before anything else happens — and on the damp, shaded and tree-lined elevations this render is made for, that step is the rule rather than the exception.
2. Prime with ATLAS CERPLAST, the key coat named for reinforced layers and mineral substrates, stocked in the exterior render primers range.
3. Stir, never modify. The paste arrives ready to use and must not be combined with other materials, diluted or thickened. Stir it immediately before use, and only at the top of the temperature range may up to 1 % clean water go in.
4. Lay at aggregate thickness with a smooth stainless steel trowel, returning surplus to the bucket and re-stirring it before it goes back on the wall.
5. Texture with a plastic float in circular motions to pull the baranek grain even. Machine-applied Gemini RS is left untextured.

Spraying runs through 6 mm and 8 mm nozzles, round or flat, depending on the unit. Wagner PC 830 and PC 1030 take 6 mm; Graco TexSpray RTX 5500 PX takes 6 mm round, 8 mm round or 6 mm flat; Graco TexSpray Fast Finish takes 6 mm flat, 6 mm round or 8 mm flat. Quoted working pressures assume standard hose lengths and are set on site once the hoses are longer. One detail repays following before the first bucket goes through: push a little CERPLAST down the hose to wet it, and it will not block.

Hand and machine develop the surface differently, and that difference can show as a slight change of colour — which is precisely why combining the two technologies on one building is ruled out. Fix the method before the first elevation. Panel planning, wet edge and trowel discipline are set out in full in the step-by-step thin coat rendering method.

Substrates, Seasoning and Priming

Seasoning times are specific rather than general, and they assume setting at 20 °C and 60 % air humidity.

Substrate	Seasoning before rendering	Priming
Reinforced layer built with GRIP U	min. 3 days	CERPLAST
Reinforced layer in ETICS, other ATLAS mortars	min. 1 day	CERPLAST
New cement and cement-lime renders	min. 7 days per 1 cm, moisture 4 %	CERPLAST
Concrete substrates	min. 28 days, structural moisture below 4 %	CERPLAST
Gypsum substrates	moisture below 2 %	GRUNT NKP or UNI-GRUNT, then CERPLAST
Plasterboard and fibre-cement boards, stably fixed	moisture below 2 %	CERPLAST
Sound paint coatings, interior only	no seasoning requirement	CERPLAST

 

Conditions, Batching and Drying

• Working window: +5 °C to +30 °C with relative humidity under 80 %, for mix, substrate and air, right through setting.
• Shoulder season: work above 0 °C at humidity to around 80 % is permitted after adding Atlas Eskimo setting accelerator, the Atlas-only cold-weather component. The seasonal routine sits in the guide to render application timing in UK conditions.
• Drying: approximately 15 minutes to surface dry and approximately 24 hours to dry at 20 °C and 50 % RH, longer near +5 °C or in high humidity. Programme to the slower figure.

Two instructions matter more on a dark elevation than on a pale one. Keep one production date across a single surface, so a deep shade holds one continuous tone across the whole elevation. And establish by trial — for this substrate, in this week's weather — the largest area you can pull and float in one cycle, then plan the breaks at corners, building returns, downpipes and colour changes rather than mid-panel, working wet on wet within each panel.

Protect worked and drying surfaces from direct sun, wind and precipitation. Gemini RS is excluded from horizontal surfaces under standing water or snow load, and from surfaces wetted by rising damp — a detail resolved at design stage with a drip and a plinth finish. Wash tools in clean water straight after use and lift hardened residue with SZOP 2000; a float that still cuts cleanly on day three is what keeps a long elevation reading as one wall.

How Many Tubs, and What the Figures Assume

Hand application starts at 2.3 kg/m², which works out at roughly 10.9 m² per 25 kg tub. For 100 m² that is 230 kg — ten tubs, or eleven once 10 % is added for reveals and detailing. By machine, 100 m² at 1.9 kg/m² is 190 kg, so eight tubs plus a spare.

• Why the machine figure is lower: a sprayed coat carries its aggregate less densely, so average consumption falls below the hand figure.
• What the figures assume: even substrates, per the ITB 2020 technical conditions for building works. The reliable number comes from a trial patch on the wall in front of you, and the render coverage calculator does the full take-off.

Ordering, Tinting and Collection From Southampton

Renders World tints Atlas and Ceresit in house, to order, on a separate mixer for each manufacturer, so a shade is mixed for the job rather than picked from whatever is already on a shelf.

• Dispatch: same day when the stock is there.
• Delivery: quoted by our team after the order rather than calculated at checkout, because render travels as parcels or pallets depending on the quantity. A 25 kg tub goes as a parcel, and next-business-day carriage is one of the options quoted. Every delivery is kerbside.
• Collection: in person at Unit 9A, Central Trading Estate, SO14 5JP Southampton, Monday to Friday 7am to 5pm and Saturday 7am to 12pm. The render is tinted at the counter and goes with you the same visit; the phone number is on our contact page.

Tinted material is mixed for your order and sits outside the 14-day change-of-mind return, which is set out in the cancellations and returns terms.

FAQ — Deep Shades, Certification and Renovation

• Four questions decide a grey-base specification: how dark you may go, what the certificate covers, whether the self-cleaning claim means anything on a shaded wall, and how the facade is refreshed years later.

How dark can a Gemini RS elevation go?

As dark as the SAH palette runs, with one condition attached. An intensive shade with a light reflection coefficient above HBW 15 needs the reinforced layer built on STOPTER K-50, STOPTER K-20 or GRAWIS U, and the GRAWIS U route needs that layer at a minimum of 5 mm with the Atlas 150 mesh doubled. At or below HBW 15, an intensive shade is limited to 10 % of the elevation. Confirm the basecoat before the shade is signed off, not after.

Is this render covered by BBA Agrément 13/5018?

No, and no BBA cover is claimed for it. Its documented system credentials are the ATLAS GRIP and ATLAS ETICS assessments. Where a UK specification asks for BBA cover, the finishes that certificate does name are the direct route, and Renders World stocks them alongside this one.

Does Gemini RS self-clean on a shaded elevation?

Three documented mechanisms sit behind that claim and they do not all depend on sunlight. Photocatalytic self-cleaning is initiated at the MIRROR EFFECT surface and does need light. The hydrophobic structure does not: it stops dirt binding and lets rain carry it off, and the render dries fast enough after rain to close the window biological growth needs. BIOSEC works independently of both, releasing biocide fastest during heavy rain. How visible the result is still depends on exposure, orientation and how much rain actually reaches the wall.

How is an aged Gemini RS facade refreshed?

By repainting with ATLAS SALTA silicone paint, one of the paints Atlas names for overpainting this render. That keeps an ageing elevation on a documented pathway, and it is a repaint rather than a re-render.

Technical Documentation

• ATLAS GEMINI RS — Technical Data Sheet (PDF, updated 14 March 2023)