Anti-Spatter has many uses the primary one is to stop the welding deposits sticking to the metal once it cools.  These deposits, commonly known as spatter or even splatter (we think it depends where you come from) is the molten metal resulting from the welding which if allowed to cool will leave small lumps on the finished piece.  This is both unsightly and, in many cases, leads to rejects.  The secondary use for Anti-Spatter is to improve paint adhearence to the weld.  This is obviously very important if the finished piece is to be painted as the SPCB Anti-Spatter will not contaminate degreasing baths and will allow the degreasing solution (dip tank, spray jet or hand wipe) to degrease properly leaving no deposits.