RickyT
Newbie
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« on: August 30, 2010, 12:37:13 PM » |
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Hi,
First off, I am a competent handyman (not professional) but have absolutely no experience with granite work.
I have black granite countertop that has a 1/4" deep chip in the surface in front of the sink that is in the center of a 10" crack. I'm hoping to be able to repair it myself. I saw that there are 'flow' type epoxies and knife-edge types. I assume epoxy is the correct way to repair this damage. If that is true, which is better for this? Water because it will flow into the 10" crack better or knife-edge because it will fill the chip better? Should I color the epoxy or will the clear be OK? Will I need to buff the top when finished to match the luster of the granite?
Thanks for your help.
Rick
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Mark D.
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« Reply #1 on: September 01, 2010, 08:13:27 AM » |
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Use a penetrating epoxy to bond the crack so it does not get any larger and then use either knife grade epoxy or knife grade poly resin colored to match the stone as the cosmetic fill. The penetrating epoxy is the consistency of water so it will seep into the crack and coat the granite, which is how it prevents the crack from growing. If the crack has made it so there are two pieces then just move the smaller piece to give you room and use a knife grade epoxy. Butter the edge of the granite and put the other piece in place, then clamp them together (bar clamps). When the epoxy oozes out of the crack use razor blades to scrape off the excess. When it is done oozing allow it 24 hours to cure and then use the polyester resin as a top coat to make it flush. The poly resin will dry with gloss. We even show this stuff in our SVS "Glues & Sealers" Here are some links: Penetrating Epoxy http://www.defusco.com/STONEWELD-CRACK-FILLER-EPOXY-24oz-1982Knife Grade Epoxy http://www.defusco.com/INSTANT-INSTALL-29-MINUTE-EPOXY-32oz-KNIFE-GRADE-2423Poly Resin http://www.defusco.com/Polyester-ResinsColor kits http://www.defusco.com/Coloring-KitsGlad to be of service, Mark |
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« Last Edit: April 19, 2011, 05:46:52 AM by Mark D. »
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creativemarbleandgranite
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« Reply #2 on: November 01, 2010, 05:58:38 PM » |
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Needs to be filled and facepolished by a pro,good luck.you will need a black color and flowing epoxy and a skilled granite tradesman,
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nssthan
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« Reply #3 on: November 01, 2010, 10:10:04 PM » |
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If I were you and this is not your trade I would only want to buy one kind of glue. Polyester will shape and shine way better than epoxy. You will probably be good with the "flowing" and simply put a piece of tape on the front edge of the crack. Make sure that the tape is sticking up past the surface, and run tape along both sides of the crack. This will allow you to fill the area. If you lightly tap on either side it will vibrate the adhesive into the crack. When the glue is hard pull the tape and use a razor blade to shave down.
Good luck. Black is tough.
Than
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Mark D.
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« Reply #4 on: November 01, 2010, 11:30:00 PM » |
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I have to disagree Nathan. If this is structural you should use epoxy to make sure the crack is bonded and will not get larger. Polyester resin does not absorb into the silica substrate of the granite and therefore is not considered a permanent glue. You can do this repair with poly and it might be fine, but it also might be like putting a bandaid on a broken arm - it looks good but it doesn't really solve the problem.
If this is a hairline crack use the penetrating since it is like water and will seep into the crack and coat and absorb into the raw granite below the surface, bonding the crack so it doesn't get larger in the future. After the crack has been structurally repaired use poly resin colored to match the stone to do a topical and aestetic application.
Glad to be of service,
Mark
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nssthan
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« Reply #5 on: November 02, 2010, 05:26:42 PM » |
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The crack is in front of the sink. It is not going to go anywhere. You have the sink to give you the structural integrity. Find out how many fabricatiors use epoxy vs polyester and/or acrylic for their seams. It has to look good. If it just had to be strong the game would change. I'd only use polyester. Glue is rated by its heat/freeze factor. If this were an outdoor BBQ MAYBE then I would agree with Mark but...
Than
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nssthan
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« Reply #6 on: November 10, 2010, 08:23:18 PM » |
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Since there wasn't much activity I thought I would share some things I found out on glue. The superior adhesion of epoxy is due to two main reasons. The first is at the molecular level, where
the presence of polar hydroxyl and ether groups improves adhesion. The second is at the physical level - as epoxies cure with low shrinkage, the various surface contacts set up between the liquid
resin and the reinforcement are not disturbed during cure. The result is a more homogenous bond and a better transfer of load between the different components of the matrix. However, two important mechanical properties of any resin systems are its tensile strength and stiffness. In scientific studies it was found that the epoxy after a seven day cure is only 20-30% greater in the two areas.
Volumetrically polyesters shrink up to 7% over time while the epoxies shrink less than 2%.
As fabricators we need to know the strengths of what we are gluing, ie. granite, marble, travertine, etc. What good does a glue that is stiffer than what we are gluing it with?
nssthan
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Mark D.
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« Reply #7 on: November 10, 2010, 11:21:11 PM » |
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Excellent evaluation Nssthan. Something else you may not know is that while epoxy tends to contract and expand at a much closer rate to the stone than polyester does. This helps to maintain a good bond between the stone and the glue. It also means that the epoxy cures less stiff than the poly does.
Mark
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nssthan
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« Reply #8 on: November 11, 2010, 07:34:38 PM » |
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Where epoxy only has a shrink rate of 2% vs the 7% of polyester is one of the places where the strength comes in. The following is a quote
"Epoxy is waterproof and avoids blsters. It is also stiffer and stronger than polyesters and vinylesther. Vinylesther poly is not half as impermeable as epoxy nor as sticky but it is a lot cheaper to buy and work with" according to sailboat magazine.
Epoxy is stiffer. Which is why for esthetic shaping ie seams and surface repairs, it would not be the adhesive/filler of choice.
nssthan
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creativemarbleandgranite
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« Reply #9 on: November 15, 2010, 06:07:08 PM » |
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use poly flowing,tint it pure black when you put the peice back together leave a small hump 1/8 wide x 1/16 tall along crack WHEN FULLY CURED take a razor and scrape ti down then face polish from 400 to die glow,that is how a pro does it .Unfortunatly its black and cracked so you will allways see it
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Mark D.
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« Reply #11 on: November 20, 2010, 09:06:57 AM » |
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Nice! I would like to point out that the person doing this in the video is a seasoned pro. If you are new at this do NOT learn how to do this by doing it on your countertop. It requires lots of practive.
Mark
p.s. - Nxxthan, they are Alpha Twisttouch, not Twincur (twincur are snaillock discs)
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nssthan
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« Reply #12 on: November 20, 2010, 02:26:37 PM » |
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Thanks Mark. Almost had poeple lookling for inline polisher heads  nssthan |
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