Cyanacrylate to Bond PMMA

What's the crack like, is it in a position where it is interfering with the structural integrity of the bench top or are you just trying to fill the crack and make it disappear?

Got some photos?

This is a kitchen counter top.The crack is very tight,but has gotten longer over time.

The light has to be at just the right angle to see it.

Replacing it would be expensive around($7K),so now that is out of my budget,since I am now retired.

I want to stop the advancing of the crack.It is curently not very visible.

The crack is very tight and both sides of the crack are level.

The counter is 30mm thick.

Can you post photos?

I am not sure what the reason is for the crack increasing in length over time (material under natural stress perhaps). Is the crack all the way through?

I think we need to answer these and other questions first otherwise the solution may not work, and you may only get one shot to get it right.

GA

Great Answer!

The other glue he wanted to use, if I remember correctly, does not set well in the presence of air and is damaged by water.....also it must have tightly fitting parts.....clean ones too.

The only bit you missed is that if he follows your advice, he should have denatured alcohol (Meths in the UK) and kitchen roll or rags to hand to clean overspill and fingers.....BEFORE IT SETS!!

Lynn is on the right track the epoxy is the answer 100% ahead of super glue, what you may consider if have a windshield repair shop drop by and see if they can inject their product into the crack. It may be difficult since it requires a vacuum followed by pressure and the crack may allow leakage. Then again you may make up a device using suction cups to straddle the crack to hold the injection cup in place while the material in injected under pressure.

After second thought there is no need for vacuum as the crack is not localized as a stone chip so any air will be forced out any way..

Lynn:

I had already been to the website and looked at the training manual.

The adhesive they use is for joining seams,and is slightly flexible.

It is too thick to do any good in this case.

The crack is too tight for epoxy to penetrate.

That is why I am considering the very low viscosity super glue.

Solar Eagle:

The warranty does not cover cracks,only defect in manufacture or materials.

The crack goes all the way through.

One of the links you provided does use super glue.

I would need a very small diamond bit to drill through the quartz,.050" or so to terminate the crack,to minimize visibility.

The crack is almost invisible,but when the light is at the right angle, it can be seen.

I think I will go with the super glue.I will clean the crack with contact cleaner and used canned air to dry it,then let the adhesive soak in as far as it will,hopefully all the way through.

Confirming lyn in #4, I would only use the cyanoacrylate if an extensive search can't find a suitable low viscosity epoxy. Cyanoacrylates are terrible as gap fillers, that is why they must have perfectly matched surfaces to eliminate bond robbing air. A low viscosity marine grade 100% solids epoxy would be the best choice.

As for the drill, a carbide drill such as used for circuit boards might work. The holes are definitely needed. The stresses that caused the start of the original crack and caused the crack to propagate would continue to lengthen despite the gluing.

Hope it works out for you.

Good Luck, Old Salt

Unfortunately (for me?) I have to agree with HTRN this time, as cyanocrylates will easily enter said crack by capillary action if it is indeed as narrow as he states. My wife has repaired cracks in acrylic painted on counter top (we are yes, way cheap here), but her work looks like stone in the end, as well as it did on day one. She is a true artiste' and I salute her for that, although she will never read this.

You could experiment with various epoxy formulations to see if there is a way to warm them up to thin them or something, but why go make a whole research project when the answer was right in your OP.

I also agree with Solar Eagle (for once or twice ) that you need to exhaust all options with the manufacturer/supplier ahead of attempting this repair. Maybe you get some scrap samples and try options on those after smashing them in half?

With the Manufacturer warranties, we have seen them get tossed by the manufacturer , who in turn, blames the installer. The cabinet tops must be sheeted with a minimum of 5 /8 exterior grade (we use 3/ 4 " Marine grade) plywood, and screwed, not nailed, into the cabinet cleats. The top must be then bedded in a certain thickness of bedding compound (latex caulk, 1/4 " notch trowel at least), without any voids. Unlike granite, and other natural stone material, which have "grain", the manufactured materials have no "shear or compressive resistance, as they are are not cross linked (Think a ceramic plate). Sometimes the plywood beneath the top has become wetland swells or delaminates, and creating pressure, or a void that increases the flaw just by the top's own weight. Pull the drawers or whatever is below the crack, and shine a light up and see if you can see any structural deficiencies, first. If it is expanding, filling the crack with Lyn's suggestion is proper, but if there is sufficient tension in the area, the crack may just reappear next to it… The small drill holes is a good one, as long as they are in the right spot. My 2 cents. Mac

This is a bit "off the wall" but you might consider using PMMA as your filler/adhesive. Starting with methyl methacrylate monomer (low viscosity should fill the crack easily) including a very small amount of an organic peroxide, such as benzoyl peroxide, the monomer will polymerize in-situ in the crack. You could carry out a few small scale experiments first, determining curing times versus initiator concentrations. No doubt a slightly elevated temperature will help too (hairdryer?). I don't know how to get hold of the ingredients but both made on a vast scale.

Had a friend 30 yrs. ago who started a windshield repair co. using this. Only hangup was regular visits and required DEA record keeping as 'methyl methacrylate' is a drug precursor....a windshield repair co. might be a good source.

Would there by any way to force what ever is used under pressure, like is done with windshield repair?

Official Retraction. See #4 Lyn for advice on pressure injection. My bad....

PMMA seems to me as the best option for repairing a PMMA countertop.

You can get PMMA in stores specialized in products for dental technicians.

PMMA (AKA: Acrylic / Plexiglass) is a two component polymer (powder + fluid) and you have to manipulate it with care. Once polymerized it can be cut, sandpapered and polished with no problems.

If you can access the back side of the crack try taping plastic film to cover it to provide an air tight membrane and hook a pump up to pull a vacuum to help whatever adhesive you select to penetrate.You might also consider using bar clamps to pull the crack closed after applying the adhesive for a better bond strength.

but my concern is:Will it bond?

At the risk of stating the obvious: whatever you choose, try it on an inconspicuous section (probably on the bottom of the work surface), before you attempt the repair.

Sounds like no one knows for sure if it will bond or not. I would use the glue you have on hand with the very viscosity and apply liberally and put your Kitchen Aide mixer over the crack and whip up some sticks of butter or something else that vibrates a lot to try to 'shake' the glue as low into the crack as it will go, hopefully all the way through before it sets up. Good Luck.

If I felt like I needed to drill a hole to terminate the crack I would do it from underneath and only go about 1/2 through to see if that works before I mar to visible surface above.

Good Luck.

Use small routing bit dremel might do it the ratio is 2/1.. 2 deep 1wide cut the crack as close as possible to the center. clean properly no dust or external material then mix and use a syringe to build a positive bead let it set and harden then start with an oxide pate and return to flat and polished. Sort out what caused the crack in the first place . Hope this helps

Thanks to everyone for all of the great feedback!

I looked up the specs on the glue(Loctite 420) I intend to use,and it can fill cracks up to .002".

It is a wicking adhesive,very low viscosity,which will penetrate this very tight crack.

This crack is Very tight,more like a hair line crack,but it starts at the edge,where it has an ogee profile and extends about 3 inches toward the center.

Even under 10X magnification,the crack line appears closed but it can be felt with a razor blade or fingernail.

If it did not go all the way through,it could be mistaken for a scratch.

However,not many elements will scratch quartz,and the crack crosses several large quartz chips.

I think it started with a chip on the edge,( creating a stress riser) and heat from pots and pans accellerated the crack formation.Even using trivets under pots,there is significant heat transfer,and coupled with Murphy's law,the factors all came together to create the crack.

I tried the glue on a spot on the bottom side,and it bonds Extremely well.

I also tried it with a fine strand of copper wire at each border to test the gap-fill strength and curing ability.

It set up and bonded the same, after 24 hours.

I used some 2 inch tiles of Silestone for this test.

The dealer said that they use the same type adhesive for repair,so I guess I am in luck.

I guess that is the best I can do.

I will post with results when available.

Thanks again everyone for the help and feedback!

Ok, there it is. Loctite.

My only comment has to do with, "the crack crosses several large quartz chips".

Quartz is good in compression but not so good in tension, so cracking across the quartz isn't necessarily surprising.

How about a before and after photo?

The quartz may crack, but it is very hard to scratch,which is why I mentioned it not being a scratch.

A photo of this very shiny surface is hard to get.

If I was a professional phototgrapher with specialized equipment,I might be able to capture the crack, but all of my amatuer attempts have failed to show the crack.

Hard to get the lighting angle just right.

Even when looking at it by eye,it is especially hard to see.

I let the loctite stand on the crack for a few hours,and wiped away the excess,then scraped off the residue with a razor blade.

Then applied a wax coat of carnuba wax.

Looks great,but time will tell if it will hold over long time interval.

Thanks to everyone for their advice and input.

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Well done! Your repair will last a long time, you can bet on that! Superglue (Ciano acrylate) and PMMA (Poly Methyl Metha Acrylate) are chemically very related, therefore there will be a good ahesion between both materials

I, for one, am glad you failed to show your crack!