Kowboy

The instructions are for amateurs.  The CA bonding is stopped by any sharp impact.  So hitting or machining the joined pieces would be a problem.  Hand sanding or using Scotch-Brite on a ROS would be fine for a pro.  If fixing a crack just inform customer to not allow a can of tuna fish to land sharply on the counter even 20 feet away for the first 24 hours.  This is over kill but maybe they will take you seriously.

Also the bond strengthens in a curve.  I can't find it now but it is something like 30% in the first hour 15% the next.  At 30% it is stronger than epoxy.  But I have had failures during shipping for pieces I machined to early.

Accelerants  will make CA go brittle over time.  I do not suggest using them.

Andy

After a few minutes your clamps are freed up and you can go on to another project. 

A couple of other considerations:

Don't try to reposition after application.  The introduction of air will weaken the bond.

Don't try to bond CA to CA, such as to bond again an accidentally broken joint.

If you want to make a Corian to wood bond with this technique:  Rub wood surface with baking soda first.  This will neutralize the acid in the wood and fill the pours eliminating the oxygen.  The baking soda becomes a hard tough plastic inside the pours and makes a very strong joint.  You would only do this for small decorative items.  Corian expands and contracts with temperature and wood with humidity.  This could cause warping in large pieces.

Ken

Ken:

According to this, CA is at full strength in two hours. Apparently accelerants do cause some loss of strength.

Joe

Joe

If you read to the bottom of that article, you will see that it was taken from Wikipedia http://en.wikipedia.org/wiki/Cyanoacrylate. If you go to Wikipedia, you will not now find that time. I do not know where 2 hours came from. When we originally started with CA we were told 24 hours. That same company now says 12. It actually continues getting stronger until the first sudden impact. The curing is on a curve that is asymptotic over time. This is true with most polymers. Even concrete continues to harden for more than 5 years, if left undisturbed. I know that concrete is not a polymer.

When curing is finished therefore becomes a judgement call. It is done when it is sufficient for your needs.

When I was in college, an engineering professor kept using the therm "for all practical purposes". A student asked what he meant by that. He answered this way. " Say I put all of the guys on one side of the room and all of girls on the other. Then asked them to halve the distance between them several times. They would mathematically never touch but in very few steps they would be close enough 'for all practical purposes'".

Ken

Ken:

Ever since I read your link and post here, I've been dying to try your technique. Yesterday, I got my chance:



This bad boy was a leaker too:



I tried to remember everything you said, but I had to get on the fabnet and your link on my phone which ran the battery down but I digress.

I set the bag of ice for not the 45 minutes you recommend, but left it for an hour and a half because I had four cooktop issues and a refinish to occupy my time. After this time and for the next four hours or so, I hit the crack with the hydrogen peroxide and some bleach cleaner the lady had under her sink. After hours of intermittent toothbrushing, the contamination went from the long black line pictured to a much shorter light brown line. It really started to fade when I sucked the peroxide/bleach mix through the bottom of the crack with my Festool vaccum.

I wasn't worried about the CA not filling the void, so after a denatured alcohol rinse and dry, I filled the gap then gently heat-gunned it shut, contrary to your instructions to heat-gun first and fill after. It worked perfectly although my concerns with tinting the CA precluded my doing so. Tinted CA will not remove or cover the remaining brown contamination.



 Although much lighter, the crack is still visible, cannot be felt, and does not leak. I used no accelerator, finally taking one of your recommendations. 

If someone would send me a cracked sink with contamination, I would like to try some dry ice on the crack and really get that thing to open up without making it worse or blowing up the sink. If the contamination could be completely removed, this thing could work really well.

While not perfect, my lady was beside herself with joy with the results considering replacing a Corian 874 runs about a thousand dollars with plumbing and all. You've made a lady in Michigan very happy and a fabricator a few dollars richer.

Thank you very much,

Joe

Kowboy

I am glad that you tried the method.  I would like to make a few comments:

First is for cleaning:

• It appears that you have hard water in your area.  That orange brown material is rust and calcium.  First cleaning with CLR or Limeaway would have made your job faster and easier.  I need to add that tip to my web page.
• If you go to a hair dresser's supply, you can get 30% Hydrogen Peroxide.  That is 10 times as strong as the stuff for cuts and bruises.  I like H²O² because it degrades to plain water which dries when you apply heat.
  

Second is on the Tinting:

• It took me a long time to find a tint that would work with CA.  I found one.  It is expensive ($100 per 2 oz)  but I only have to use a few drops in each bottle.

Third on the application:

• The moisture in the crack combined with those parts that were already tight and the heat applied, set the CA before the crack closed.  This held it open and appeared dark.
• It is important to close the crack first.  Our CA is the thinnest made and has surfactant action.  It will seep through the closed crack.  This and the tinting eliminates the discolored crack.

I hope this helps.

Ken:

Thanks for the follow-up and suggestions.

The CA took twenty minutes or so to dry, so I don't know how it could have solidified and held the crack open when heated.

On certain cooktop failures, there is heat distortion of the solid surface. All the clamping in the world is never going to pull it back together. I'm wondering if this isn't somewhat the same with cracks, only on a much smaller scale.

Joe

Joe

CA does not bond in the presence of oxygen.  So that which was on top just dried and that could take 20 minutes.  But some that was below the surface probably did.

The heat distortion that you see is annealing.  The Corian polymers get more tightly packed with each heating cooling cycle.  If you heat the area moderately (with a hair dryer not a heat gun) you can usually get a crack to close even .016" by expanding the Corian in the area.  An epoxy seam adhesive is not usually strong enough nor does it get into the finest area of the crack, to hold when the material goes back to size.  Our CA is 3 to 5 times as strong as an epoxy for this. 

Several years ago I had a customer who did not repair the underlying problem.  He did not sand out the tooth marks or add tape to the cook top hole.  He called back two years later to repair a new crack about an inch away from the original.

Mr. Ken Dolph,

This is a fascinating thread! I love the things you are doing!

I am guessing the CA works pretty  well wth acrylic, but maybe not as well with Polyester.

What are your thoughts?

Its the old mechanical vs chemical bond thingee!

Please advise!

No, your eyes are not decieving you. That's a white Corian top with a painted Faux finish the lady did herself. She is pleased as punch. However, she is not as happy with the epoxy she sprayed on the sink:



She hired me to grind it off:



There were some big 'ole contaminated surface cracks, but in these antique 3/4" thick Corian sinks you can grind away without fear.




I even ground the disposal flange. It shines up pretty by the time you Scotch-Brite it. When she saw the result, she put her hands to her face and said "Oh, my God!" That's always a good sign.

It took about an hour and a half.

Joe

That was a "Great Save" Joe!

Lenny:

It ain't all that but it pays mighty good for a boy with no college education.

Thanks,

Joe

Here's that "annealing" thing Ken spoke of. This took a 12'x12" piece of cuttiing board to repair. It's from the cracked sink job.

Joe

Kowboy

That is a great example.

Lenny

We have had few failures. Most of them were in polyester material. Some were in material that I could not determine the composition.

Joe,

Your college educated, you just haven't graduated yet.

Nice job on the sink. Is it a solid surface countertop with a faux finish?

Posted By Andy Graves on 01 Nov 2011 03:31 PM
Joe,

Your college educated, you just haven't graduated yet.

Nice job on the sink. Is it a solid surface countertop with a faux finish?

Andy:

Thanks and yes.

Joe