SPR Black is a suspension of molybdenedisulfide powder in water with a detergent. The powder particles adhere to a fingerprint as does a fingerprint powder. The gray, shiny prints that are developed with SPR can be lifted (after drying) with Gellifters, Instant Lifters or tape.
Powder suspension can be sprayed, but small articles can also be submerged in it (after diluting the ready-to-use B-86000). The SPR method has the advantage that it can be used on wet and/or dirty/greasy surfaces.