The Number on a Roller Blind Fabric That Nobody Explains
Somewhere in the fabric book, next to the colour name, there is a percentage. Three per cent. Five per cent. Ten per cent.
Nobody explains it, most customers do not ask, and it ends up being the single biggest reason people are unhappy with a blind six months after it goes in.
That number is the openness factor. It is the proportion of the woven fabric that is hole rather than yarn. A five per cent fabric is ninety five per cent thread and five per cent gaps you can see through. Blockout fabric is zero. Everything else sits on a scale, and each step along that scale trades one thing for another.
What each range actually does
At one per cent you are close to opaque. You can just make out shapes through it in bright conditions. Glare is almost entirely gone, but so is any sense of what is happening outside, and the room feels closed even though light is technically coming through.
Three per cent is where most people should land for a living area with a difficult aspect. Enough view to know the weather and see movement in the garden, enough density that you are not squinting at a screen. It is the least exciting answer and usually the right one.
Five per cent is the popular choice and the most commonly regretted one. It reads well in the showroom, where the sample is held up against a north window on a mild day. Fitted to a west facing living room in February, it lets through enough direct sun to make the television unwatchable between four and seven.
Ten per cent and above is a view fabric. Use it when the outlook is the point, when glare is not a problem, or on a south facing window where direct sun never arrives.
The mistake almost everyone makes
White fabric looks cleaner in a sample book, so people choose white.
Then they discover that a light coloured screen scatters the light coming through it. The whole surface of the blind glows, the view behind it washes out, and the glare you were trying to solve has been replaced by a large luminous rectangle on the wall.
A dark charcoal or bronze screen in the same openness does the opposite. It absorbs rather than scatters, the fabric surface stays visually quiet, and the view through it is noticeably sharper. Anyone who has looked out through a dark flyscreen and then a white one already knows the effect.
The catch is heat. Dark fabrics absorb more solar energy and re-radiate a portion of it into the room, while light fabrics reflect more of it back at the glass. So the fabric that gives you the best view and the best glare control is also the one working hardest against your air conditioning.
There is no clean way around this from the inside. Fabrics with a metallised or light coloured backing get you part of the way, giving a dark face to the room and a reflective face to the glass. Beyond that, if heat is the primary problem, the answer is shading outside the window rather than a different roller fabric.
Where the dual roller comes from
The reason so many Sydney homes end up with two blinds on the same window is that no single openness figure covers both jobs.
A screen fabric handles the day. It cuts glare, keeps the view, and gives a degree of daytime privacy because the outside is brighter than the inside. A blockout fabric on a second roller handles the night, when that brightness relationship reverses and a screen fabric stops hiding anything at all.
This is worth understanding before you commit, because a dual bracket changes the depth of the headbox and the reveal has to accommodate it. Retrofitting a second roller into a recess that was measured for one is possible but rarely tidy. Most people who order roller blinds for a main living space and then decide six months later that they also need the blockout end up paying for brackets twice.
The other detail worth checking
Openness is the number people miss, but fabric weight is the one that determines whether the blind still looks good in three years.
Light screen fabrics on wide windows sag and cup at the edges over time. The fabric no longer sits flat against the tube, and you get a slight curl down each side that catches the light. On anything above roughly two metres wide, ask what the tube diameter is and whether the fabric is rated for that span. A larger tube costs very little more and is the difference between a blind that hangs flat and one that does not.
Also ask which way the fabric rolls. A standard roll drops the fabric behind the tube and sits closer to the glass, giving a smaller light gap. A reverse roll runs it over the front, which clears deep window handles and architraves but pushes the blind further into the room. Fitters usually default to one without asking, and on the wrong window it either fouls the handle or opens a visible gap.
In short
Decide the openness before the colour. Look at samples in the room they are going in, at the time of day the sun is worst, not under showroom lighting. Then choose the shade that suits the room, knowing that darker will almost always perform better than it looks like it should.
Image note: one featured image. A close range shot of a screen fabric with a view visible through the weave, ideally showing the texture of the yarn. A second image comparing a white and a charcoal screen on the same window would carry the article's main point if the site allows two.
