I'm not an expert in modelling, in fact this is my first time using top coat. And it is not disappointing for me to spend my money for top coat.
I believe many modellers out there use top coat for finishing their models. The purpose of using top coat is to prevent paint from scratching off easily.
But after reading some books, I found that top coat can 'hide' little scratch as result of sanding.
All my models are brush painted (no enough money to buy airbrush), and the major problem of brush painting is, the paint isn't smooth as painting using airbrush. This can be seen when painting a big area.
So, for those who brush painted their models and had same problems like me, you should try using top coat.
The picture above is a part from my HG Strike Noir. You can see the surface isn't smooth (if you can't, click on it).
And this is after I sprayed it with top coat. Its so smooth as airbrush painting.
But, there are 3 types of top coat, and there are also Mr. Super Clear that do the same job. Which one to use? What is the difference?
Point no.1 - both top coat and Mr. Super Clear has 3 types: Flat/Matt, Semi-Gloss, and Gloss.
Above is comparison of lightning between the 3 types. Above: Gloss, Middle: Semi-Gloss, Bottom- Flat・Matt.
I prefer flat because for me, Gundam is not a sports car. I don't like glossy Gundam. But everyone have their own opinion.
And above is the comparison between Top Coat [A] and Mr. Super Clear[B] (both flat).
Left line is painted using Gundam marker, middle:Hobby Color, right: Mr. Color.
Another problem is, Top Coat take a very long time to dry.
There are also many infos on top coat if you search the internet.