Tips on gluing rock?

[inachu]

When gluing rocks together should the spot be free of everything just pure rock?

Like should coraline algae be removed to do it?

 

[jhildebrand]

No, you can glue on coraline. Take off any soft matter or debris though. It works a lot better out of water. I take a paper towel to the spot first to get any moisture off the rock before gluing.