Quote Originally Posted by ic-racer View Post
Blue or cyan filters have no effect on VC or non-VC paper. They block light outside of the paper's sensitivity spectrum. The paper doesn't know or care
Cyan, yes (in theory; in practice a cyan bulb, especially one made for non-photographic purposes, might not be pure cyan and so might have some effect). Blue, no. VC papers are sensitive to blue and green light, so if you use a blue filter (which blocks green and red light), you end up changing the contrast, since you'll be reducing the amount of green light that hits the paper.

The OP identified the bulb as blue. If that's accurate, I'd expect it would have some effect. Of course, people often misidentify cyan as blue; or the color might be light enough or impure enough or affect only certain frequencies and so have little or no real effect. Testing is the only way to be sure.