Over my extended absence three different readers wrote in to say they were having buttercream consistency problems, specifically with the Swiss and Italian meringue buttercreams. All three reported that their buttercream was working well for spreading and cake building, but piping was a problem. Their piped decorations were drooping and/or losing their sharp edges. Can IMBC and SMBC be firmed in any way?
I can think of a few ways to achieve a firmer buttercream texture. One is to scale back the butter a bit, but just by a little, maybe 15% or so. That raises the ratio of meringue and gives the buttercream a bit more body. The other thing you might try is to buy higher quality butter, which tends to be firmer. Lower quality butters tend to have lower melting points, which makes them softer at room temperature. That tends to be truer in the winter months when dairy cows aren’t grazing in the fields as much, but inexpensive butter can be soft at any time of year. “Spend more money” is never welcome advice, but where buttercreams are concerned you tend to do better when you pay up a bit.
However if an all-butter buttercream isn’t strictly necessary, you can swap out some the butter and replace it with shortening. This is a lower cost option for sure, and a time tested tactic that works well for many bakeries, including some higher-end shops. Mixed with butter, the shortening isn’t as apparent, though there is still that bit of greasy mouthfeel that I don’t much care for. However if you’re looking for a quick and easy way to prevent your piped decorations from drooping in a warmer environment, shortening may be the way to go. Substitute it for up to half the butter in a recipe.