Marc;
Hi! As noted, it appears white in the bottle. That is because these acrylic "clear flat" paints do have some solid material in them. They are NOT like applying distilled water or straight paint-thinner or alcohol to a kit.
It will provide a softly "flat" coat when applied - that flat property is the result of a reduced load of semi-transparent "matte" - a finely-ground neutral-color pigment - combined with a low-sheen vehicle or fluid base for the paint (having a suspended pigment material is the critical element to get a flat finish - which is why flat paints dry flat. They have thin, low-sheen vehicles and a large load of finely-ground pigment. Glossy paints include a high-sheen vehicle component to add on that shine over the pigment.). So, the more you put on, the more pigment you build up. Apply a lot, and you will get an increasing "dusting" - a lightening effect rather like spraying on very thinned white paint! And as noted before, avoid pooling, as this will produce light "tide marks". The darker the base coat being covered, the more risk of both lightening effects and tide-marks being visible.
When I use this stuff, it's applying it in very thin coats over the entire kit, letting each dry completely and determining whether an additional coat is desired. Using some "stand-off" distance will enhance the dulling effect for the amount of clear flat applied.
I have found that you can actually get a better "flat" effect by mixing the clear flat about 1 in 3 with Future! Makes for a nice, hard, finely-flat coat!
Good luck! Bob