How well did you shake it before spraying? Gloss paint needs to be applied with a wet coat. If you put it on too dry, it will look flat or semi-gloss. Likewise, too wet of a coat of flat paint will take on a semi-matt finish.
The likely cause is that the paint was applied too thin per coat or the nozzle was too far away. A coat thick enough to get a glossy sheen is seen but not too thick that runs develop is the proper technique. Practice on a similar surface is suggested.
Dull gloss
It can also appear where the top coat is applied in damp or frosty conditions; or where the finish is subjected to dampness or frost during the early stages of drying.
Flat and matte paints offer no light reflectivity, while semi-gloss and high-gloss paints reflect light, giving them a slight shine. Depending on what you decide will suit your room, several finish options can offer the perfect sheen to fit your style preferences.
One thing that determines the finish of any paint is the number of pigments in its mixture. The more pigments you have in the paint, the flatter it will look on your wall.
As semi-gloss has a higher sheen than satin, it can affect how the color appears on the wall once painted. Semi-gloss bounces and reflects light around a room, so if your space has lots of lights and lamps or plenty of natural sunlight, the end result can be a little different to the color on the tin.
Flat, eggshell and satin paint are best for interior walls, whereas semi-gloss and gloss paint are best for trim and woodwork.
Semi-gloss paints have a slightly glossy appearance and are less reflective than gloss paints. They offer good stain resistance, are easy to clean, and are most often used in rooms requiring frequent scrubbing, such as kitchens and bathrooms.
Patchiness usually happens if you don't use enough paint, or apply it unevenly. Using a touch more paint, and painting in small sections one at a time, usually does the trick. Also, rolling in a grid fashion will get you an even finish too. But, sometimes, changes in the gloss level leave things patchy.
To achieve even more gloss, apply a high gloss varnish once the painting is finished and the paint is dry. There is a product by Liquitex that is both a gloss medium and varnish, so you could use it to mix with the paint as well as use it for a final coat of varnish.
Some paints adhere extremely well to certain surfaces while others need a rough or scuffed-up area for the best application. For example, when working with bathroom trim or kitchen cabinets with semi-gloss or high-gloss finishes, you'll most definitely need to sand between coats.
So, semi-gloss is a higher sheen paint than satin; thus, it's typically easier to clean it without making it lose its shine. If you have kids and need to wash the stains from the wall surface regularly, semi-gloss paint will be a better option than satin paint.
Semi-gloss Finish
This paint finish is just glossy enough to make it easy to wipe clean, yet it won't look too shiny. One of the best paint brands with a wide selection of colors is Benjamin Moore.
Even more reflective than satin with a smooth sheen, semi-gloss paint gives rooms a shiny, sleek appearance. Because it offers high resistance to moisture, it works well in areas with higher humidity, such as bathrooms, kitchens and laundry rooms, as well as high-traffic spaces like doors and utility rooms.
A semi-gloss paint finish will read "shinier" than an eggshell. The shinier finish gives it more durability - making it even easier to clean with a harder dried film that is tougher and can take more wear and tear, but there's a downside. The more reflective the finish, the more imperfections it will show.
Semi-gloss is best used on doors, trim, bathrooms, and kitchens. Cons: It will still reveal some of the imperfections in whatever surface it is painted onto. It will also easily reveal every brushstroke and you can always tell if a roller brush was used to apply it.
Semi-gloss
Due to its durability, it's recommended to use this finish in places that frequently need cleanings, such as kitchens, bathrooms, and utility areas. However, this finish also shares high gloss's disadvantages. Because of its shine, it will easily draw your attention to the imperfections on your walls.
SEMI-GLOSS
pros: Reflects a significant amount of light and is easy to clean. cons: Reveals every imperfection in your walls, every brushstroke, and the frequent “orange-peel finish” of a roller brush. where to use it: It's ideal for doors, trim, casework, bathrooms, and kitchens.
Try one of the versions of melamine-foam-based white sponges (“Magic Eraser” is one brand) –these are least likely to mar flat-painted surfaces, but due to their ablative action (they wear away) may leave a white residue on darker colors. Just follow them with an absorbent WHITE towel, using a gentle blotting action.
Cleaning walls and trim will remove grime, cobwebs, dust and stains that can prevent your paint from adhering. Use a mixture of lukewarm water and mild soap, gently rubbing in a circular motion. Rinse your walls using a slightly damp cellulose sponge.
If plain water doesn't work, try adding vinegar to your damp sponge or cloth and gently scrub the walls. If vinegar doesn't remove the stain entirely, use an eraser sponge for problematic spots. This gentle cleaning product should eliminate the stain without damaging your flat paint walls.