Both can be diluted with water, however: - Once dry acrylic is indelible while gouache is not, - Acrylic allows obtaining volume and dimensional effects (especially with the gel auxiliaries and mortars). Gouache does not. - The appearance of the gouache is also unmistakable: extreme depth and colour intensity, very matte and smooth finish.
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I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.