How to apply fiberglass backing to marble?

[jpvonoy]

I am not a stone worker, but I have a customer with some marble slabs.  Some of them have a fiberglass backing on them, and the fellow who applied it for her has passed away.  She would like the rest of the slabs to be done as well so she doesn't crack them (they're sitting on stands, being used as tabletops, and sometimes get moved around).  I have experience with fabrication of carbon fiber/fiberglass race car parts, so I have some cloth, mats, and resins around.  Questions:

1.  Do I need a special resin designed for stone, such as you sell, or can I use a standard aerospace grade epoxy or polyester resin?

2.  Do you recommend a cloth or a chopped strand mat, and what thickness of fiberglass is desired? (2x3 ft slabs, 3/4" thick)  The current pieces she has are backed with a mat, but I've been reading that epoxy is recommended, and epoxies usually aren't compatible with mat.

3.  The undersides are currently a mat finish, unlike the top which is polished to a shine.  Would I need to do any further roughing or prep of the surface before applying the backing?

4.  I've read that marble is very pourous, do I need to worry about bleedthrough?

If I do need to prep the stone or buy a special resin, please let me know which of your products you would recommend.  Anything else I should know? 

Thanks much!
Jeremy

[nssthan]

I tried to do a little research and didn't find out very much.  Here is some food for thought.  For physics to work for you with a fiberglass backed product the supports need to be on the ends and the middle unsupported.  Otherwise the backing does not add any structural integrity.  Secondly, miost adhesives will not stick very well to a honed surface; therefore, you will need to do something to prep the surface like use a cup wheel.  Lastly,  I would use a polyester.  Epoxy will stick to either epoxy or polyester.  However, if you were ever going to laminate the edges at a later date and you used epoxy for the backing and the future fabricator used polyester for the laminating, it wouldn't work.  Polyester does not adhere to epoxy.

My 2 cents -- unless they are VERY large pieces it is not worth fiberglassing it.

nssthan

[Mark D.]

But if it is something the customer wants we sell the fiberglass mesh for doing this.
Resining should be dones with epoxy as it will breathe (contract and expand) at the same rate as the stone so it won't eventually fracture.
If you have questions about how to do this please call me during the week at 800-289-6834.

Glad to be of service,
Mark

[jpvonoy]

Thanks for the replies.  I will call you this week Mark.