I am modifying a fountain, by adding spouts, made of shaped copper. I need to attach the spouts to the stone bowl, but am not sure how.

  • The fix must have a watertight seal with the stone, that is, the glue/mortar/filler must fill the small gaps between the cut stone and the copper shape
  • It must also prevent ingress of moisture which will freeze in winter and push the spout off
  • The fix must provide mechanical strength
  • The fix must be resistant to weather and both standing and running water
  • The fix must be flexible as the stone and copper will deform at different rates as it heats up and cools down over time

I have tried building mastic but it doesn't cure (its been over two weeks) as only small areas are exposed to air. I have also tried heating with a heat gun and it just makes it even softer.

What do I use to attach copper to stone?


You don't seem to be using the RIGHT mastic, or "construction adhesive". Construction adhesive (ie PL or similar brand name) would be about the best material for the job, because copper is a REALLY DIFFICULT material to bond to.

Try experimenting (with scrap) with other brands or types of mastic/adhesive. Certain types of PL should set up near-hard within a couple of hours.

  • This is it. I foolishly thought since mastic is naturally occurring the products based on it must have fairly similar properties. Using another (Gold Label Pond and Aquarium Sealer) and they are already fixed. Thanks! – sebf Aug 24 '14 at 12:16

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.