What published gloss ranges can and cannot tell you
GlossAtlas turns two published ranges into a verdict such as "strong overlap". This page puts numbers on how far that verdict can be trusted and where it stops, using the whole dataset as the test bench. Knowing the limits of a method is part of the method.
1. Overlap is a generous test
A published range is a specification, usually written as two numbers a few units apart. The median width is shown below by sheen name (the width of a range is its highest value minus its lowest).
| Sheen name | Ranges published | Narrowest | Median | Widest |
|---|---|---|---|---|
| Flat | 9 | 3 | 5 | 7 |
| Matte | 7 | 2 | 3 | 5 |
| Eggshell | 8 | 5 | 6.5 | 12 |
| Pearl | 1 | 10 | 10 | 10 |
| Satin | 8 | 5 | 10 | 10 |
| Semi-Gloss | 8 | 10 | 10 | 15 |
The engine scores overlap as the shared width divided by the narrower of the two ranges, and calls it "strong" at 50% or more. That choice has a consequence: a range that sits wholly inside a wider one scores 100%. For example, Sherwin-Williams Emerald Flat is published at 0–4 at 85° and Valspar Signature Flat at 0–7. They share 4 units, which is 100% of the narrower range, though the Valspar range is 7 units wide against 4. Both statements are true, and a reader should know the second one exists. This is why every result page shows both ranges and the shared span, not only the label.
2. Most results are strong overlaps, and that is not the same as most matches being good
| Result | Readings | Share |
|---|---|---|
| Strong overlap | 80 | 81% |
| Partial overlap | 7 | 7% |
| Nearest range, no overlap | 12 | 12% |
| No close equivalent (gap over 15) | 0 | 0% |
Each target brand has eight or nine finishes in the dataset, spread across the whole sheen ladder, so some finish usually overlaps. That is a feature of the question ("is there a finish at this brand that covers these values?"), not evidence that the brands are alike. The informative results are the 19 that are not strong overlaps, and the ties.
3. Ties are the rule, not the exception
In 59 of 99 readings, the best-ranked set contains more than one finish. Some ties are mundane (a brand's two lines publish the same range), others are ties on the engine's ranking between different ranges (for example two ranges that both lie wholly inside the starting range, so both score 100%, or two at the same gap). The result names every tied finish rather than picking one by an arbitrary rule. When GlossAtlas names two finishes, the right reading is "either is as close as the published numbers can say", and the choice between them is a question for the manufacturer's other attributes, not for gloss.
4. When there is no overlap, how far apart are the best candidates?
| Gap (gloss units) | Readings |
|---|---|
| 0 (ranges touch at one value) | 4 |
| 3 | 2 |
| 5 | 4 |
| 10 | 2 |
No gap reaches the 15-unit threshold beyond which GlossAtlas would say "no close equivalent", so that label never fires on this dataset; the threshold is a disclosed policy choice, not a measured one (methodology). A 10-unit gap, the largest here, is not small: it is the width of a whole Satin range.
5. What the sheets do not say
The data is only as informative as the manufacturer's sheet. Across all 33 records:
- Base and colour. 33 of 33 sheets do not say whether the range applies to every base or colour. Gloss readings can depend on the tint.
- Test standard. 33 of 33 sheets do not name the test method. The usual conventions are ASTM D523 and ISO 2813, but GlossAtlas does not claim a sheet follows them unless it says so.
- Tolerance and batch variation. A range is a specification, not a guarantee about the can you buy.
- Appearance. Perceived sheen depends on the colour, the surface preparation, the application and the lighting. A gloss unit is a reading from an instrument, not a description of a wall.
- Independent measurement. None of the 33 records comes from anyone other than the manufacturer. GlossAtlas has not tested paint.
A practical way to read a result
- Look at the two ranges and the shared span before the label. A narrow shared slice of two wide ranges is a weaker match than the same label on narrow ranges.
- If several finishes are named, treat them as equally close on gloss and decide on other grounds (price, coverage, base availability).
- If the result is "nearest range, no overlap", read the direction and size of the gap: "5 units glossier" is a different decision from "10 units flatter".
- Buy a sample in the lighting of the room. The comparison narrows the choice; it does not replace looking at it.
The worked examples apply these steps to real choices: Emerald Satin to Benjamin Moore, Marquee Satin to Sherwin-Williams and Signature Satin to Behr.