what  advice do my fellow fabricators gave to customers regarding boiling water
going straight into a solid surface sink?

The standard advice is to run cold water, mixing it with the poured water.

I do this, but with acrylic sinks, I'm not too sure it's even necessary.

The big no no would be having a bunch of ice in the sink for awhile and then pouring the boiling water.

Actually it is the acrylics that are more prone to damage from boiling water. It is seldom a single event. It is the repeated expansion due to heat that will cause the little spider cracks in the bottom, around the basket. Acrylic has a larger coefficient of expansion than polyester.

Running cold water while pouring the boiling water eliminates the thermal shock.

Tom, I'm with you on the ice advice.  I always tell customers:  If they are going to melt ice in your sink, to do it right away, not after it has sat in the sink for several minutes, or hours.  And to avoid thawing frozen food in the sink as well.  Doing so just increases the risk of thermal shock damage.

Ken, I agree that the effects of thermal shock is cumulative.  My theory on the cause of the spider web crazing at the drain, or anywhere else, is this:  When the surface of the sink is exposed to extreme high temperatures it may actually harden the resin and reduce its elasticity.  At some point the surface refuses to expand at the same rate as the rest of the sink and the surface will develop crazing.  The crazing most often starts at the drain because of the hard corners of the profile at the recess for the drain flange.  I have also seen it under Inst-Hot dispensers.  (Lenny?)

As Joe showed us a short time ago.  The crazing might be able to be sanded out but it takes considerable skill and effort and there is no telling how deep the crazing is before you start.

Johnny C

Acrylics and poly-blends both craze.

The drain is a natural place that is conducive to craze formation. As the part expands from the heat, the drain hole becomes larger (stretches). You undoubtedly get some degree of "strain hardening" which I think is what Jhon C may have been referring to.

 Eventually after many cycles some chemical bonds rupture placing stress on the adjacent chemical bonds which also rupture until a small micro crack forms. This is called initiation and is not visible to the naked eye. Once you achieve initiation the next phase is called propagation (the crack grows). Propagation is spontaneous. It can't be stopped. The craze will continue to grow.

While it is possible to sand out a highly visible craze, it isn't practical IMO, as John C pointed out, you have to remove the entire craze which is extremely hard to do unless one happens to have an electron microscope and/or psychic abilities.

For what its worth, I knew a guy once who every day religiously sanded around the sink drain with some scotch-brite. He wanted to polish the area to remove any invisible micro-cracks (the initiation phase) which is the only phase you have any real control over. He had that sink for decades, and never had a craze.

Ken,
Interesting you say that. In my experience the amount of crazing problems in poly blend are overwhelmingly greater, especially considering the volumes sold of acrylic versus poly blend. No comparison.

I wonder why there is a difference in our experiences?

Tom

You may be right. I was just going by the thermal expansion coefficient of acrylic versus polyester. Even granite mountains erode to beach sand by thermal expansion/contraction among other factors.

Do polyester sinks ever crack through from this crazing?

I don't usually get involved with sinks until they are cracked through. With information from the DuPont labs and the aircraft adhesives industry, we developed a repair for acrylic sinks. It has proven itself over the last 15 years.

I don't think it will work with polyester though.

I run the water just to make me feel better. I don't know that it actually does anything but can hurt to cool the boiling water a little.

Ken<
i have seen the old fountainhead sinks crack all the way hrough< but it is usually the crazing that ruins the sink>

what is this acrylic repair you speak of?
Inquiring minds want to know.

Tom

Here is a link to my instructions. 

http://sites.google.com/site/coriar...ack-repair

They may be simplistic but they were designed for amateurs.  I know that there are pros who say that this cannot work.  I can just say that we have been offering this for 17 years.  I did a quick calculation.  We have sold about 10,000 units.  Our customers have repaired cracks in sinks, around cook tops and other problems. About evenly divided.  So that makes more than 3,000 sinks.  We have gotten 6 reported failures.

The adhesive is not certified.  I learned of it from Dr. Slocum, Corian's inventor. Because of improper techniques it was rejected by fabricators more than 40 years ago.  DuPont labs had recommended it over epoxy when they tested it.  However there are specific techniques which the fabricators did not understand and they had failures.  We solved those problems.

How deep do you feel the CA gets with this technique?

Tom,

To answer your question i will give you an example.

A fabricator friend of mine had always humored me whenever I spoke of this technique. One day I was going to visit him for an off cut that I needed.  He asked me to bring a bottle of the adhesive.  When I got there, he had a Staron top that was 3/4 finished.  They had cracked it down the middle for about 30".

As soon as I arrived, he waved his hand.  15 fabricators came over to watch a monumental failure.  I had them clean and clamp the piece. I applied the adhesive.  My friend said " that did not go through!" He wiped his hand under the repair and glued his hand to the bottom of the counter top.  He was surprised but not sold.  We hand sanded it and they could not find the repair.

He since has said that each bottle has saved him $1,000 in repairing shop problems particularly chip out.  The most important things to remember are:

1) Tight seam

2) No moving or machining for 24 hours.

3) Above 35% relative humidity at time of application.

To better answer your question - I tested the wicking by laminating a piece of Lexan to Corian.  After preparation and clamping, I applied it to the edge.  The glue went in irregularly from 3/4" to 2". 

Ken

"He wiped his hand under the repair and glued his hand to the bottom of the counter top."
Heh.

"He since has said that each bottle has saved him $1,000 in repairing shop problems particularly chip out."
Hmm, not sure I'd want to buy a top from this guy.

So you are saying the adhesive penetrates even after the clamps are applied? Do ou use any pressure, or does the surface tension do it?

Tom,

The  adhesive is never applied to an open seam.  After firm clamping, a fine bead is applied to the top of the joint. The capillary action will even draw the adhesive upward. If left undisturbed for 24 hours, the resulting joint is 3 to 5 times as strong as any epoxy.

As far as the tightness of the joint, it is not unusual for the clamps to fall off as the adhesive draws the joint together.

This is the same technique used in building jumbo jets.  Welding and riveting cause stresses in the metal which can precipitate metal fatigue. 

I have 1/4" but joints which, because of the application, flex every day for the last 15 years. These are in full sun with temperature variations from 0 to 120 degrees F with no failures.

Ken

Ken,
Can you explain this quote from you instructions "Apply a very thin bead of Art Specialties International, Inc. Super Thin CA (tinted if this is a solid light color)".  Is this your product,or just regular CA?  What are you using to tint the CA?

John

Wayne,


Our CA is manufactured for us to be acrylic compatible with high surfactant qualities.  The tint is a titanium dioxide suspension which allows for a month shelf life.  Our CA typically has a six month shelf life. Only enough tint is added to make the adhesive translucent.  So it works with a wide range of colors.

Ken

We use thin ca and it will wick right through a tight seam. Put the Parrallign clamps on the two pieces and clamp together. Add ca and it will wick through and bond tight. Only drawback is the cure time.

On lightweight stuff, you could probably get away with sanding in a few hours but the strength comes when you wait.

Ken:

This is fascinating and I can't wait for an opportunity to try it. However, a two trip job is almost always economically unfeasable for me. Have you tried any of the CA accellerators?

If I could get to one trip, it would be like a license to print money.

Joe