Small Particle Reagent (SPR)

• Used when item is wet or on wet surfaces
• More commonly used over Sudan Black
• Reacts with Lipids/fats
• Non-porous surfaces
• Can be sprayed using a spray bottle, a compressed-air spray system, or dipped if small enough
• SPR is Molybdenum Disulfide MoS₂
• 'Dabbing' powder technique best used with this technique

PROS -

• Easy cleanup - soap and water
• Can be used underwater
• Immediate reaction

CONS -

• Very messy
• Stains
• Needs gloves and safety glasses

PROCEDURE:

1. Spray print with SPR [mix 1 ounce of MoS₂ + quart of water + 2-3 drops PhotoFlo]
2. Rinse with water
3. Only the MoS₂ remains on print
4. Photograph print
5. Dry
6. Lift print