Description
Atlas Gipsar Uni is a white finishing skim: the last, thin coat that turns a sound wall or ceiling into a smooth surface ready for paint or wallpaper. It comes as a dry powder in a 20 kg bag, you mix it with water on site, and each coat goes on up to 2 mm thick. It is a finishing gypsum plaster to C7/20/2, reinforced with polymers, and it stays white once dry. Find it with the other finishing plasters and fillers at Renders World.
What Atlas Gipsar Uni Is For
Gipsar Uni does one job and does it on a wide choice of walls: the final smooth coat. In its own technical sheet, Atlas marks it for these jobs:
- Finishing skims on interior walls and ceilings.
- Full-surface skimming of plasterboard, to finishing levels Q2 to Q4.
- A base for paint and wallpaper once the skim is dry.
It goes on concrete, cement and cement-lime plaster, gypsum plaster and plasterboard. For three other jobs the same sheet points to Atlas Gipsar Plus instead: levelling an uneven wall first, filling small holes, and taping plasterboard joints. So if the wall needs more than 2 mm to come flat, level it first and finish it with Gipsar Uni.
Why Choose a White Finishing Skim
- White and smooth — selected fillers free of impurities give the skim its white colour, a clean base for paint.
- Glides under the trowel — the mix holds its water and spreads easily over the wall.
- Harder surface — a high share of polymer resins gives strong adhesion and a harder skim.
- No shrinkage cracks — the skim resists cracking as it dries.
- Low dust when sanding — it sands by hand or by machine.
- Trowel, roller or spray — for roller work Atlas recommends a scotch-brite type pile roller such as the Atlas Rollo Finish roller.
Atlas Gipsar Uni Technical Data
| Property | Value |
|---|---|
| Type | White finishing gypsum skim, dry powder |
| Made from | Anhydrite flour, polymer resins, lime fillers and additives |
| Classification | Finishing gypsum plaster C7/20/2, PN-EN 13279-1 |
| Pack | 20 kg bag |
| Coat thickness | Up to 2 mm per coat |
| Consumption | About 1 kg per m² for each mm of thickness |
| Water | 7.8–8.0 l per 20 kg (0.39–0.40 l per kg) |
| Soaking time | 5 minutes, then mix again |
| Working time | At least 1.5 hours after mixing |
| Adhesion | At least 0.50 MPa |
| Working conditions | +5 °C to +25 °C |
| Application | Trowel, roller or spray machine |
| Reaction to fire | A1 |
| Shelf life | 12 months from the production date on the bag |
| Goes on | Concrete, cement and gypsum plaster, plasterboard |
How to Apply the White Skim
Get the Wall Ready
Because each coat is at most 2 mm, the wall must already be flat. It also has to be stable, dry and clean: no dust, dirt, lime, oil, grease, wax or old oil and emulsion paint. New Atlas cement plaster needs at least a week for every centimetre of thickness before you skim it. Treat mould first with Atlas Mykos Plus, and protect any steel that the skim will touch against rust.
A wall that drinks water fast takes Atlas NKP primer straight from the can, or Atlas Uni-Grunt Ultra. A smooth wall with low absorbency, or one with a layer that weakens the bond, takes a bonding coat of Atlas Ultragrunt.
Mix the Skim
Tip the powder into a bucket holding 7.8–8.0 litres of water for a full bag, and mix by hand or with a slow drill and paddle until it is free of lumps. Let it stand for 5 minutes, mix again, and use it within about 1.5 hours. Work in a clean bucket: set gypsum left from the last batch makes the new one set faster.
Apply and Finish
- By trowel. Use a smooth stainless steel trowel and smooth the surface as you go. Run strips up the wall from floor to ceiling. On a ceiling, run strips from the window into the room and draw the trowel towards you. Trowels and spatulas are in the skimming blades and spatulas range.
- By roller. Spread the mix evenly with the pile roller, then smooth the coat with a stainless steel trowel as soon as you finish rolling.
- By machine. Hold the lance 1 to 1.5 m from the wall and spray in horizontal, overlapping strips, then level with a steel trowel straight away. Atlas names the Wagner PS 3.39 and HC 950 and the Graco T-Max 506, Mark VII and Mark X, with the main filter taken out. If you stop for more than an hour, clean the hopper and hose with fresh water.
- Sand. When the skim is dry, sand it with a sanding machine and discs of grit 180 to 220, or by hand with paper or mesh. Fill any flaw with a thin fresh coat on a dampened surface and sand again.
- Paint or paper. Prime the dry skim with the primer your paint maker names, then use an acrylic or latex paint, or hang wallpaper.
While the skim dries, keep direct sun and draughts away and air the room. Wash tools in clean water as soon as you finish.
Which Atlas Skim Fits Your Wall?
Three Atlas skims on the Renders World shelf, each with its own lead job:
| Skim | Comes as | Per coat | Lead job |
|---|---|---|---|
| Atlas Gipsar Uni | Powder, 20 kg bag | Up to 2 mm | A white final skim on a wall that is already flat |
| Atlas Gipsar Plus | Powder, 20 kg bag | Up to 5 mm | Levelling, filling small holes and finishing from one bag |
| Atlas GO! | Ready-mixed, 25 kg bucket | Up to 3 mm | A top finish rolled straight from the bucket |
For taped plasterboard joints, use a joint compound such as Atlas GTA first, then skim the whole board with Gipsar Uni.
How Much to Order
Gipsar Uni uses about 1 kg per m² for each millimetre of thickness:
- 1 mm skim — about 20 m² per 20 kg bag.
- 2 mm skim — about 10 m² per bag.
Orders are processed the same day when the stock is there, and the team quotes delivery after the order. You can also collect in person from the Renders World counter in Southampton during opening hours.
FAQ — Atlas Gipsar Uni
How far does a 20 kg bag go?
About 20 m² at 1 mm thick, or about 10 m² at 2 mm.
How thick can one coat be?
Up to 2 mm. A wall that needs more than that to come flat is levelled first, then finished.
Can I fill holes with it?
Atlas sends filling small holes and levelling to Atlas Gipsar Plus. Use Gipsar Uni for the final smooth coat over the repair.
Can I skim plasterboard with it?
Yes, over the whole board, to finishing levels Q2 to Q4. Tape and fill the joints first with a joint compound such as Atlas GTA.
Can I use it in a bathroom?
No. Gypsum skims are not for bathrooms, laundries or rooms that stay above 75 % humidity for long, or for walls exposed to direct moisture.