I need tips for creating a certain material

mslft

I have been struggling getting the right look for a specific material-- old machinery -- and would really appreciate any tips or insight.

Here are some photos. There are several reference photos, and  2  examples of materials I have made (attempting to emulate the look of the surfaces in the photos). 

https://imgur.com/a/9A4Sa2W

I am using Quixel Mixer and Blender. As far as I can tell, the surfaces I am trying to create are cast, unpainted, bare iron or steel, with a very light oxidation or rust, almost a powdery coating. Due to the nature of being cast metal the surface is not perfectly smooth and therefore not very reflective, but the granularity is fine enough to be used for machinery. They are metal but not very reflective. They have rust but are not totally corroded. 

I guess the first question to ask is if my assumptions about the original surfaces are correct. I only show 2 examples of results but I have tried many more, none of them look right. Either too reflective or too dull. 

Eric Chadwick

Well, lighting will make a huge difference in the perception of whether a material is accurate or not. 

Get a good quality HDRI to check your model in. A quality "studio" environment is a must for accurate material creation and judging.

Put a couple calibration spheres in the scene, and adjust lighting until they look good... a 227-white sphere, 187 gray, 30 gray, a chrome ball, a glass one.

We put some guidelines up here on our wiki, search for PBR.

mslft

That's helpful, I never thought of that approach... thank you! I will look at the material you suggest