We've been buying the basic plastic tank garden sprayers for applying flame retardants, but the retardants seem to gum up the pumps in short order, often after the first use. I'm tempted to invested in a proper, metal tank Hudson sprayer for this application, but I don't want to waste my money if I'm only going to have the same problems. I'm hoping that someone here might have experience using a metal tank Hudson sprayer to apply flame retardants, or might have tips/tricks to unclog one that has been gummed up by such products.