Help with Corian Plaque

[Don Williams Michigan]

I have to mount a corian plague to a smooth concrete pillar. Yesterday I used Lexel adhesive on both clean surfaces. Clamped in place for 60 minutes. Today, plaque could be pulled off and lexel material still soft.

This is a high traffic outside area. Can you provide any advice for fastening the corian to the concrete? It is a vertical placement and mounting area is flat and smooth.

Thank you for your help!

[Dan Hintz]

It should always be a bit soft as it's a rubber, similar to a new application of silicone.
How long did you leave it to dry?
Did it rain, or was the pillar wet?
What was the outside temp when you applied it?
Had the pillar been sitting in direct sunlight?
When removed, was the adhesive still sticking to both the pillar and the sign, or just one? Which one?

[Don Williams Michigan]

Dan,

Clamped in place for 60 minutes. Then left to dry for 24 hours. It did rain during that 24 hour period.
Both surfaces were clean and dry when Lexel applied. Outside temp was 80 degrees with high humidity.
Lexel material is stuck to both surfaces. Obviously, the corian plaque slid out of place sometime during the 24 hour period. I was able to lift it right off when I went back to verify adhesion.

[Dan Hintz]

Is the column directly in the weather, i.e., did the rain fall on the plaque? Was the sun hitting the column before install?

I ask because Lexal doesn't mix well with water, and if you installed it on a really hot surface, it's adhesion ability is severely decreased.

If the adhesive was stuck equally to both surfaces (and was still gooey), it didnt cure. It's an air-dry adhesive, so how much surface area did you give it to dry from (i.e., was it a large plaque)?

[Don Williams Michigan]

Sun was hitting the column. The material was still gooey and did not cure. Plaque was 5 x 7 inches. Rain could have hit the plaque as it is in an open area.

Can you recommend a different adhesive? It will be hot and humid here for quite some time and I have to get the plaque in place.

Thanks,

[Dan Hintz]

I can't suggest a different adhesive, but others might. I would suggest trying again, but this time install early in the morning before the sun has had a chance to heat up the column. Cover with a few sheets of paper/cardboard to keep direct sun off of it for at least 24 hours. No need to clean the area of the dried Lexel as it will stick to itself.

[Scott Shepherd]

Something that small, VHB tape and it'll be stuck for a long, long time.

[Keith Outten]

The Dupont Corian Installers Manual reccomends silicone adhesive. You should clean the Corian surface with alcohol before you apply the silicone.
For Corian to Corian the Dupont adhesive is the best, for small parts like pen blanks you can use CA glue.
For Corian to acrylic use Dupont adhesive, the next choice would be silicone.

Don, in the past I have used Loctight construction adhesive to adhere Corian door signs to painted cinder block. When I had to remove a sign I had to break the Corian sign into about eight pieces. The problem you face is an exterior concrete surface that can suck up moisture like a sponge and it could take several days of dry weather before the concrete loses all of the moisture.
.

[Ken Dolph]

I agree with the VHB tape. Silicone does not adhere well to unsealed concrete.

I had a customer 15 years ago who wanted to use Corian a the water level of his pool. He was using it to replace the tile that is usually used there. He did his home work and found that Goop by Eclectic Industries was perfect for this application (Corian to Concrete) . I got a call from him 12 years later for more Corian. He told me that he had made one mistake. He had tightly butted the 8 foot strips. Every day the strips would press out in the middle as they were heated by the sun and expanded. But he was happy. There was no failure of the Corian or the adhesive.

You may want to use small dots of adhesive to allow for air curing.

Ken

[Ken Dolph]

Keith

I have to disagree with you on the DuPont Seam Adhesive. DuPont Labs recommended industrial CA for Corian. However they never gave the installers proper instruction. CA needs 35%+ relative humidity at time of contact, and 24 undisturbed hours for full cure. Any sudden impact, such as machining, during that time stops the reaction at the level reached. The resulting bond has about 3,000 lbs/sq in psi tensile strength. A MMA epoxy (DuPont Seam Adhesive) cannot exceed 800 lbs/sq in, and should be undisturbed for 24 hours to achieve that. Both cure rates are logarithmic and they achieve about 75% of full strength in 12 hours.

Since the fabricators did not know this they had spotty results and abandoned CA as a joke very quickly.

I got this information from Dr. Slocum the inventor of Corian. I later had this confirmed by a very old fabricator.

[Don Nicholas]

Clean the Concrete surface to remove any concrete dust. Use Silicone and VHB tape to hold it in place. If the design of the sign would allow, you could use SS screws with recessed finishing washers with screw anchors in the wall.

[Keith Outten]

Ken,

Thanks for the information, I will keep it close by.

I have had excellent results using Dupont's adhesive when I need to adhere Corian to Corian. In fact I doubt it can ever be pulled apart the bond is so strong. My latest test was to adhere two small pieces of Corian end to end. I pushed the 3" wide pieces together with my hands squeezing the glue out and left it sitting on my bench for two hours without using any clamps. The two pieces are about 4" long and I could not break the glue joint so I am pleased with the results.

As I mentioned before I use LocTite adhesive to adhere Corian signs to painted cinder block several hundred times per year. I have never had a sign that a student could remove from the wall, they can destroy them but they can't remove them.

I know that lots of people use CA glue as a Corian adhesive. I have concerns over the long haul because CA glue tends to crystalize after several years. I don't have personal research to rely on, this is what I have read in several cases.

I machine keyholes on the back of almost every Corian sign I make no matter if I plan to use adhesive or not.
.

[Ken Dolph]

BHB should be enough. Just make sure that the plaque is undisturbed for 72 hours for full strength. Per 3M instructions.

http://multimedia.3m.com/mws/mediawebserver?mwsId=66666UuZjcFSLXTtnXfcoxfyEVuQE cuZgVs6EVs6E666666--&fn=70070940609.pdf

[Ken Dolph]

Keith

We must have been typing at the same time or I would have answered you. CA crystallizes if you use accelerant or introduce oxygen once the polymerization has started. It starts when one part sits tightly on another. I do not know the exact distance. If there is no moisture (35%+) at the joint at bonding it will not be waterproof. Wiping with 70% alcohol is a good prep.

As to the longevity of the bond. Airliners have been CA bonded for the last 20 years. Welding and riveting causes stress in the metal and metal fatigue. They typically use the wicking grades 98%+ pure. This allows them to put the pieces together first and them apply the adhesive. This way there is no chance of oxygen intrusion. It can soak 2 to 3 inches into the joint. I have put Lexan, acrylic and glass to Corian Watching it wick is phenomenal.

When I first started using it, I could not figure out why my clamps were always loose when I came to take them off. Then I put a piece of 1/4" Lexan together with Corian. There was a Corian chip about the size of a grain of salt in the joint. The CA flowed up to the grain, around the grain and snapped the Lexan over the grain. Ahah! the joint shrinks during bonding.

I hope you liked my story.

I do the keyholes as well.

Ken

[Don Williams Michigan]

Thanks to all who responded. I really appreciate the input.