About 4 years ago, I had a Corian shower installed because I preferred it to tile/grout. I thought that the technology allowed for the (essentially) PERMANENT bonding of Corian to Corian so I had 3 small corner shelves installed to hold soap, shampoo, etc. Now, one shelf has fallen off, one is about to fall off and the third is now questionable. The corner shelves are just small flat pieces of Corian about 3/4" thick that fit into the corners - no bracing underneath of any kind. When I look at the edges of the shelf that fell off it looks like they attached it in several "spots" with a clear material which is now quite hard (silicone? hot glue?). What is the best way to attach corner shelves in this shower so they stay permanently fastened? What design and what bonding material and how do you hold it up there until it dries and will stay in place?

The original design was flawed. To get you right get some small pieces of coreion or even a marble door threshold/the big box stores. Cut that down marble small brackets to fit under the shelves. Lay shelf flat siclicone those brackets under the shelf. Be accurate and so it square and plumb let dry Now to install get junk lumber or furring strips (Big Box) and cut those to proper height to set the self. Clean off old silicone and apply new to self edge and bracket edges. Gently push into shower wall and rest it on wood braces. Have ready duct tape and long strips tape from below and up over the shelf. This will help make minor adjustment and hold it to keep pressuring the shelf against shower. The marble can be cut with a Little diamond blade on a grinder or circ saw. Use whatever for a bracket even a tile if you like.
Good Luck
Hope I helped Signed 21boat

There is a specific epoxy that is used to bond Corian to Corian. Try contacting a good kitchen center in you area. I believe the product runs about $8.00 a tube.

You can get the duPont joint adhesive at the following link
http://wwwcoriartspecialties.com

They will also advise youon the best installation techniques.

I hope this helps