Help! Cracked sink!

claudia_sandgrowerOctober 24, 2009

My bathroom vanity has a granite top with an undermount china sink. The sink is cracked - no idea how it happened; I think it was a manufacturing flaw that slowly grew worse (I didn't notice it for nearly a year). Now it's gotten so bad that the sink is leaking slightly. I used an epoxy radiator repair putty underneath (not Mighty Putty - got this from an automotive store) but the crack is still growing. Replacing the sink might be impossible - the top and sink came already put together from Lowes. Can the sink be replaced? Can it be repaired?

Here is a link that might be useful: Vanity top w/sink

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Internal stresses will most likely cause the crack to continue growing.

    Bookmark   October 24, 2009 at 11:33PM
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The sink should be replaced. Look underneath and you'll see mountung brackets.

    Bookmark   October 25, 2009 at 12:44AM
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I have heard of sinks cracking because the drain hardware was installed to tightly. It may not show up right away but constant too much pressure will make cracks, and once they start they don't stop.

    Bookmark   October 25, 2009 at 10:50AM
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I posted the below in the Bathrooms forum... just thought to make a repeat...

Claudia - you post a link for (the sink you purchased??) at $198.

Can your sink be replaced? Well, this depends on how it is attached. The link you post states the sink is attached. HOW is it attached?? Metal clips, with screws??? You would have to take a look... For $198 - you could replace it all, and just reconnect plumbing.

Can sink be repaired? Yes. Sink (per link) is made of Ceramic. It would be hard to reglaze, and obtain an undamaged appearance, and would cost more than an entire new ensemble.

Now, can you fix this?? Yes - you can. But, you would have to be willing to let the repair be visible. Sink would be functional.

First thing - you state using an epoxy - but the crack is still 'growing'.

So, we have to figure out WHY crack is still growing. Is it because the sink is inadequately supported?? The vanity the sink rests on bangs against the wall??... WHY is the crack still growing. If the sink does not bounce, seems to be adequately supported - than the crack is probably growing from the vibrations of the water pouring into it.

A typical crack - at its end is approximately .0001"

This means that if you have a sheet of metal, (steel, aluminum, whatever) rated @ 60,000lbs per sq inch - if you have a crack in that steel - a force exerted in the area of the crack - of 6lbs or more - WILL propagate and continue the crack...

If you do not wish to buy a new sink, and wish to STOP the crack, and not have it leak anymore; than do the following...

1. Examine the sink carefully for any missing supports. Make sure the sink is properly supported. Add additional support if it seems necessary.

2. Examine the crack for the starting point, and the end point. If the starting point is where the drain line connects up to the sink (possibly because the drain line was tightened to much into the ceramic) - it will be very hard to seal the crack, since it changes direction radically at the drain line, and that area must have a flange tightened and connected to it...

3. Assuming the crack is in the middle of sink, or does not radically change direction from going horizonatal down to vertical because of drain line...

4. What you need to do - is to STOP DRILL - the crack. You can do this if the crack starts at the drain line as well - but my concern is the sealing of the crack around the drain line.

5. Any place where the crack ENDS because it runs out of material (it is at the ceramic bowl edge) - it does not need to be stop drilled.

6. Where the crack exists in bowl material; and the crack can continue growing - to stop it - you MUST stop drill it.

Stop drill is where we throughly examine a crack and determine its end. It is preferred to use a 10x magnifying glass. But with some BRIGHT light, and a good eye, you can generally see (determine) the very, very, very END of a crack, even without a 10X.

You now take a 1/4" MINIMUM drill bit; (3/8 would be better); and DRILL a HOLE at the END of the crack. If you have more than one crack end (crack has forked) - do this also at that crack end. Again - you do NOT stop drill where the crack has run out of material...

7. You then take the hole you have drilled, and fill it with epoxy; or whatever waterproof material that you wish. you also apply waterproofing material to the entire underside of the crack along its length, and doing so on the top of the crack would be good as well. Epoxy can be dyed with even some normal food coloring dye if you wish, for more of a color match.

Stop Drilling the crack - will stop the crack from continued growth. How this works - is to force the lines of force (water vibrations) which are following the crack (and continuing its growth at its very end (.0001") - to now flow around a much larger surface area. Because you put a HOLE at the end of the crack. For the crack to continue - the lines of force must now take in much more surface area of your ceramic bowl - and still manage to continue the crack around the hole which you put in...

I know this seems counter intuitive. But it works. It is used in Jet Aircraft repair all the time - to stop a crack from growing... A doubler is than added, but you don't need that for this application.

So, if you want the sink, don't care tremendously about the looks; but want a sink that is water tight - do the above. The crack will then be fixed, and your sink will be water tight.

    Bookmark   October 25, 2009 at 3:12PM
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"It is used in Jet Aircraft repair all the time"

Cracking in porcelain is not the same as cracking in aluminum.

    Bookmark   November 27, 2012 at 1:10PM
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I can't possibly see how you could do a satisfactory repair by stop drilling. OP could replace sink and possibly even whole top much more simply.

Before jet aircraft, stop drilling was used in nautical repairs. I used it on an ABS pool part with some two part resin, and it never leaked again.

A ceramic sink is kind of a different animal.

I would say the drain nut was overtightened.

    Bookmark   November 28, 2012 at 4:17PM
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Had you follow instructions before using epoxy plumbing Fittings to repairing your china sink?

In the case of epoxy radiator repair putty require some precautions.

    Bookmark   March 7, 2013 at 7:18AM
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