...it was the only time I used ModelFlex for chipping and it was the perfect chance to experiment. They don't chip too badly but not super fine like Tamiya and isn't as easy to control either.
*
The very thing that makes Vallejo such a strong and resilient paint is the very thing that makes them a lousy choice to chip with. I have a German 250 half track I chipped using Vallejo Model Air white and I really had to work at the surface to get through, then once through the paint came up in big pieces. It was like a switch, on or off. You can see it in ScaleModelMedics video where he chips the muffler. Not only does he go at it with a toothpick but you can literally see large flakes of paint lifting.
I've chipped a ton of paint jobs with hairspray and the chipping fluids, and in all my experiences, with Tamiya, you actually start to see through the paint before it starts to chip, which can be such a cool effect in itself, that semi translucent worn look so you don't have stark bright white next to stark underlying color paint. Nothing about that looks real in scale, the white wash needs to look like it's slowly wearing/washing off, not flaking off clean, in big pieces. There weren't big white flakes of paint lying around the battle field. When the Tamiya does start to chip, it starts very small and fine and this is all with the lightest of pressure. By lightest, I mean almost none, simply moving a wet brush across the surface begins to take the smallest of chips. When working in scale, this is exactly what you want if you want it to look real. You can start small and fine and work up from there, with most other acrylic paints, you don't have that control.