PBR amount sliders relationship to amount maps

Question

Hello, 
 I am trying to better understand the relationship of the amount sliders vs the texture maps/masks for the PBR materials (but it is probably also applicable to the traditional sliders) 
 Help just mentions that "it" is a linear grayscale texture; 0% (black) indicates off and 100% (white) indicates on, but it does not explain how the slider works with the texture pattern. 
 Ie. I might prefer to balance the exact nature of my white to black values in the texture maps in 3rd party applications, but when I add the texture to my MicroStation material I have no idea where the slider should be to act neutrally and just let the texture do the work. A slider set to 0% seems to turn off the map entirely, set to 100% seems to blow out the values. 
 Is the slider Adding, Multiplying, or doing some other operation to the values in the texture maps? 
 Would it not be useful to change the 0 to 100% values on the slider (which make sense when no texture map is attached) to a positive / negative "gain" set of values balanced in the centre of the slider at 0 (neutral)? 
 Regards 
 Robert

David Trejo-Rodriguez · Answer

Robert Jones said: Help just mentions that "it" is a linear grayscale texture; 0% (black) indicates off and 100% (white) indicates on, but it does not explain how the slider works with the texture pattern. 
 Is it just the metallic slider scale you are concerned with or also the roughness, glow, etc that concern you? 
 Running some test using the delivered example i dont get the blow out you are reporting. if you would like to share the files you are using would be glad to test it. 
 Robert Jones said: A slider set to 0% seems to turn off the map entirely, set to 100% seems to blow out the values. 
 From the test I ran its a multiplying of the texture map being used by a value ranging from 0 to 1. so 50% would be .5 times the texture map values. 
 Robert Jones said: Would it not be useful to change the 0 to 100% values on the slider (which make sense when no texture map is attached) to a positive / negative "gain" set of values balanced in the centre of the slider at 0 (neutral)? 
 With the above in mind i would say your suggestion wouldnt work. My knowledge on texture maps is limited but from my understanding in rendering the values range from black to white, using a gain could push those values out of the acceptable range resulting in possible artifacts.