A lot of seaming questions

[GlennH]

I apologize if this has been asked before.  A quick search of the history did not turn up what I was looiking for.  What brand of expoy is preferred for seaming Tenax or Stoneweld?  I have been very exacting with my seams all are 1/16 or less.  I want the best color match to make them dissappear even more.   I understand the color gets added to the epoxy before it is mixed with the hardener, but is it possible to add spots of color with a toothpick or something to the mixed product after it has been applied, but before it hardens?  Once the epoxy has hardened, does it have to be polished to match the granite better?  If so what is used for polishing in terms of tools & compounds?

Last question.  I believe it is desireable to have the granite glued down firmly to the countertops prior to seaming it.  I can get more epoxy in the seam if I glue the granite down and seam at the same time.  Is this necessary?  Or does capillary action draw enough epoxy in the gap to completely fill it?

Thank you

[Mark D.]

Do you want to use epoxy for your seams? Polyester resin works faster and is much easier to use and clean up. More fabricators use that than epoxy for a seam.

If I were doing a seam with epoxy I would use Instant Install. Since it dries so fast you are not waiting a couple of hours to finish your seams. Here is a link:
http://www.defusco.com/Glues:-Epoxy,-Polyester,-etc.-Epoxy-for-Natural-Stone/c82_500/p2423/INSTANT-INSTALL-29-MINUTE-EPOXY---32oz-KNIFE-GRADE/product_info.html

Rather than a toothpick (which will put holes into the seam prior to getting hard) why don't you dab it on with an artist's brush? I have heard of people doing this but I personally am not very artistic.

You can easily make the poly resin shine more by buffing it with extra fine steel wool. Both epoxy and poly resin may be top polishes ( if you know how to do that) to increase the gloss level.

More counters are adhered to the substrate with silicone caulk than with ANY glue. That is the preferred way to install a counter to the substrate.

Glad to be of service,
Mark

[GlennH]

Thanks Mark.  I am not well versed on the pros and cons of polyester vs epoxy.  From your response it would seem that polyester is easier than epoxy.  Easy is not always better.  Which is recommended for durability & color matching?  If polyester is the choice what is the preferred brand & hardener combination?  Thanks for the tip for the artists brush.  I am not artistic either.

[Mark D.]

You use the same colors to dye both glues. While I would never recommend poly for a lamination since there is structural integrity involved it is the glue of choice by most fabricators for doing a seam. Just to be sure we are on the same page I define structural integrity like this - if the glue bond comes loose will anything fall? If the answer is yes then you MUST use epoxy on granite. Since a seam is supported from beneath if the glue bond came loose nothing will fall so there is no structural integrity.

Now that we are on the same page here is why poly is easier:
1) It sets up much faster than epoxy. Usual 15-20 minutes with a cure time of 2 hours while the fastest epoxies for stone take 29 minutes and have a cure time of 18-24 hours.

2) you can clean it up with acetone or denatured alcohol. There is no solvent for epoxy once parts A & B have been mixed together.

3) You can adjust the shine up or down with steel wool when using poly resin. With epoxy it is more difficult. While both will dry with gloss it does sometimes need to be adjusted to match the factory finish on the slab.

4) There is something else. Let's say the countertop moves for some reason. If you epoxy the seam and something breaks it is going to be the granite. Usually the break will happen right next to the seam as epoxy dries stronger than granite. The reason the granite breaks is because the epoxy will absorb into the silica substrates in the granite while the poly resin will not (the same reason you cannot use poly for a lamination). If you use poly resin in the seam and something moves then the poly seam will pop which means you have to adjust the top and razor blade a top coat of poly on the seam to make it look right.

All in all I recommend poly over epoxy for seams unless you are a seasoned veteran in stone installation.

Glad to be of service,
Mark