This primer is a acrylic primer. That's what the polyurethane means. This means that it's not very durable as it's grip on the plastic is weaker. Acrylic paint will not damage the primer and neither will enamel paints. Lacquers are a bit trickier as too much will melt the primer (and possibly the plastic underneath) and cause the paint to become splotchy. However, if you bump a key or something hard onto the bare primer, it will scratch. It is not very durable at all. This issue is reduced when paint is applied as the top coats will harden and help protect the kit. If you try to sand this primer, then you'll probably fail. Because it gets damaged so easily, the sandpaper will only do that more. The black primer is probably the worst in tone. I can understand if white takes many coats, but this also needs many coats! Otherwise the primer looks dark blue-ish gray. Just go with a Tamiya spray can primer.

I love this Vallejo primer and use it for most builds.

Used Vallego primer for my second model build. I have to say this primer is really good. It is easy to use in an airbrush. Thinned it 50/50 with x20a thinner and it worked perfectly. Put it on in layers and got an even coverage on the model.