Brian suggestion of making a second material with a bump only and no color (or any other attereibute) normally works, but NOT for the Bhodinut (SLA) shaders. Try it with the Danel Glossy shader for instance. Make your second material with bump only and add it to the right of your Danel material (make sure “mix textures is UNCHECKED). Just a black material, right? NOW go back to your bump material and check “Alpha”. Select “color” from the pulldown menu and set it to 50% grey. Rerender. Voila! There’s your bump. Hope this helps!