Microwaving colored buttercream does indeed brighten the hue of Swiss meringue buttercream. We'll go over the general technique and why this happens. We'll also cover some common questions about this technique, such as if this alter the heated buttercream in terms of volume, or if you can skip all of this and just color the meringue.This technique is great for European buttercreams (Swiss, Italian, French, German). American buttercream is a different breed of frosting, and has a different set of rules that I didn't cover in this video.