Regardless of what you call it, cement, adhesive or glue, if it is not used with discretion, that sticky liquid can do more harm than good when splicing a conveyor belt.

The popular opinion among many belt splicers and even some belt manufacturers, has always been, “if a little cement is good, then a lot of cement is better”. I assure you that nothing could be further from the truth. And the truth lies in knowing what rubber cement is and what role it plays in conveyor splicing.

Rubber cement that is used in belt splicing usually consists of 10-20% rubber compound dissolved in 80-90% solvent. When the volatile solvent evaporates or as is sometimes said, “flashes off”, all that is left is the rubber compound. The only role rubber cement plays in belt splicing is to hold all of the components of the splice together until it can be secured in the press.

That’s right folks; its only job is to hold the splice straight and true until it can be clamped in the platens of the press. Rubber cement plays no role in how tightly your splice cures. That may be difficult for many of you to comprehend because you have been told throughout your career that “more cement is better”, “you gotta slather it on like your basting a turkey”, when in fact the opposite is true.

I know because I’ve seen it first-hand. In a local shop I participated in an experiment where one splice was painted, as normal, with cement, while another splice was assembled with no cement at all. The post-cure results? Identical adhesion values for both splices. Fresh tie gum, fresh cover stock and properly stripped/cleaned belt ends/carcasses are all that is required for a strong, long lasting splice.

Why am I telling you all of this? Simply to remind you that a very little bit of rubber cement goes a long way. We have recently seen a series of splice failures with one common factor tying them together. The splice technician applied a coat of cement that was too thick and the solvents could not “flash off”. When a heavy coat of cement is applied, the top of that coat skims over, giving the appearance of being dry while underneath, much of the solvent remains. If a belt is cured with solvent remaining between the plies, the solvent will expand when heated causing delamination of the splice components and subsequent splice failure.

To forego this possibility, dip your brush in the cement only ¼”, tap the brush on the can and apply the thinnest coat of cement possible with vigorous brush strokes to spread out the cement and allow ample time for the solvent to evaporate. You will know the cement has dried thoroughly enough when it is tacky to the touch but leaves no residue on your finger.

Be mindful of how much cement you apply and you will be one step closer to eliminating splice failures forever.