What makes a good seam in granite or quartz?

oldryderFebruary 11, 2013

I am a fabricator.

"I know that one part of the process is that they vibrate or shake the one piece agaist the other for 30 min" - this is ridiculous. I am an engineer and formerly worked at a company that makes stone countertop machinery and this is simply not correct.

there are a few things that make a perfect seam:

1. the edges to be mated must be perfectly vertical and flat. there are a few ways to accomplish this depending on the fabricators equipment. many shops only go "1/2 way" and skip the steps that make the edges perfect.

2. the top edge of the seam must be chip free. again there are different ways to accomplish this but many shops simply leave the edge irregular. you see pics of this often on GW. Not all stones can be make perfectly chip free but most can if the fabricator is willing to take the extra time. The main reason quartz seams look so good is that the top edge doesn't chip even with simple sawing so it doesn't take extra effort to make the seam good.

3. a perfect seam is perfectly flush across it's entire lenght. This can be impossible as natural stone slabs are often not perfectly flat. Quarts is better in this respect because of the way it's manufactured. when there is a step at a seam a good installer can often eliminate most or all of it if he has the correct seaming tool which actually allows him to bend the stone very slightly. Some granite shops will grind a seam after install but IMHO it can be near impossible to work the top surface such that the worked area is invisible from every angle in every lighting condition. (Note: some fab shops regularly grind seams and say it turns out perfect. I'm a non believer.)

4. The grain transition across a seam is often the most conspicious aspect of a seam. Good fabrication minimizes this but it's almost never perfect. Again quartz has an advantage since even the newest quartz colors have very little movement compared to actual stone.

5. the exposed edge of a seam should be flush on the bottom. since slab thickness can vary sometimes the fab shop has to grind the underside of the pieces meeting at the seam so the bottom of the joint is flush. Only a hack shop leaves a step on the bottom of a seam.

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Thank you, oldryder. This is helpful to be armed with as I meet with KD and fabricator tomorrow about the poor seams and chips in my granite.

May I ask whether the equipment/method necessary to ensure a vertical, flat and chip-free edge is something that most fabricators would have, or does this process require expensive equipment that only the larger fabrication companies would have?

    Bookmark   February 11, 2013 at 11:11PM
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"May I ask whether the equipment/method necessary to ensure a vertical, flat and chip-free edge is something that most fabricators would have"

Most shops, even relatively small shops that only do a few kitchens per week would have the necessary equipment. A bigger problem is that many shops don't spend the extra time it can take even though they have the equipment.

    Bookmark   February 12, 2013 at 11:33AM
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More great information, thanks again oldryder!

How does hardness or softness of the stone (guess there's middle territory there too) affect the seam making when working with granites?

    Bookmark   February 12, 2013 at 2:29PM
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"How does hardness or softness of the stone (guess there's middle territory there too) affect the seam making when working with granites?"

only to the extent that hardness correlates with "chippiness". in general harder stones are "chippier" but it's not a consistent relationship. Some relatively soft stones chip because the inclusions pop when you saw it.

hope this was helpful

    Bookmark   February 12, 2013 at 4:39PM
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Any thoughts on this seam and patch at the angle? I just can't get myself to like it. And I'm wondering why it was necessary to do the angle anyway; was to get a mitered look?


    Bookmark   May 29, 2013 at 9:50PM
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I think I have a very good seam. I have seen better, but I'm very happy!!

    Bookmark   May 29, 2013 at 10:17PM
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janeflaherty: the joint is horrible. It was not cut correctly and the chip was obviously just glued back in. terrible workmanship.

teachertile: thats a pretty good seam.

    Bookmark   June 27, 2013 at 5:18PM
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Terrific thread, thank you! Do you have any guidance regarding seams near sinks and rangetops (which don't have countertop in front, only in the back, like my KA 36")? My cooking wall run is 126", the sink run is around 104". The slabs are long enough to do without seams but I'm not sure my fabricator/GC will, he said something about "always" seaming around sinks.

    Bookmark   June 27, 2013 at 5:41PM
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IMHO Seams at sinks and cooktops are to be avoided primarily because it can be difficult to get a really nice seam on a narrow piece.

Occasionally a seam at a cooktop (a "rail" in the front and back of the cooktop) is preferable because it allows the elimination of a full seam somewhere else. Consider a 148" run with a cooktop. Too long for no seam so maybe you seam at the cooktop instead. The cooktop usually covers almost 1/2 the seam in the rails once in place.

Some fabricators seam undermount sinks at the sink. I believe they do this because it eliminates the possibility that the fabricator will have to deal with a cracked sink rail which happens sometimes for no apparent reason and can be very expensive for the fabricator. Personally I think putting a seam in the busiest part of the entire kitchen is a wrong approach.

Farm or apron sinks are seamed in the back because you can't make a long sink run with the huge cutout and relatively narrow back rail a farm sink cutout requires.

When possible, a really fussy fabricator will make the sink area (left, back, and right pieces) out of a continuous section of the slab so the grain of the stone is not interrupted at the seam behind the sink.
my 2 cents

    Bookmark   June 28, 2013 at 2:34PM
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Holly- Kay

Old Ryder, Thank you so much for sharing your knowledge with the rest of us on GW. My cook top area has two seams. I don't know why they did it that way but they were so well done that I had to look for them. I have a total of four seams but only the one was problematic. Thank goodness it is being resolved.

My fabricator made the apron sink look great because of the way he left the piece seamless.

    Bookmark   June 28, 2013 at 4:40PM
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