Seaming Solid Surface Countertops

Splines aren't recommended, but a seam block is (and other tips). June 12, 2014

I'm working on a Corian countertop for an island that is 52" x 96". In addition to the seam of the 2 sheets of Corian, I'll be miterfolding the edges all the way around so the top appears to be 3-1/2" thick.

I used to work with Swanstone several years ago and we always used to put a spline in the joint when we seamed two sheets together. Is this necessary? I watched this video and they aren't using a spline and the joint shows incredible strength.

I made a test piece with Corian without a spline and I was able to break the joint without much effort. I only used spring clamps but I thought that should have been adequate. Has my adhesive gone bad? It has been stored above 70 degrees and it's about 6 months old.

Forum Responses
(Laminate and Solid Surface Forum)
From contributor J:
We have been doing Corian and other solid surface for many years. For doing a spline in the joint, I would not recommend that at all and would maybe void the warranty. I would use a wavy edge bit for the seam, make more glue contact, and do a 4'' seam plate on the underside. Always cut the plate at a 45 angle. Check the glue, as we have been having some problems with the hardener not coming out in older tubes. Purge it before you install the tip; it seems to set up in the tube and we have to take a small drill bit and open the hole up.

From contributor A:
I have to agree with contributor J, with the possible exception of the wavy edge bit - it's not really necessary. A good straight edge is fine, but the advice of using a seam block and purging the adhesive tube is 100% correct. You should also be cleaning the contact areas with denatured alcohol before applying the adhesive. Dupont has some very specific requirements for fabricating Corian, and it is best to follow them.

From contributor P:
Thanks for the responses. I understand the seam block - but I'm not sure what you mean by cutting it at 45 degrees.

Also, I'm wondering if my adhesive has gone bad. It says not to store it above 70 degrees, and it was 95 in the shop a few weeks ago - although when I'm actually gluing, it's only about 75 degrees. Have you ever had adhesive go bad or is it probably just a mixing problem (maybe the hardener isn't getting released in the right ratio)?

Thanks again - I'm fairly new to solid surface. I am not a licensed Corian installer because I'm just doing commercial work, which they don't warranty anyway.

From contributor J:
The seam plates we do are ripped on a 45 degree on the table saw, then glued to the underside of the top. I have no problem with hot weather storage in the tubes. My main problem is that in the tubes, the hardener has been setting up. I always put the grey cap that the tubes come with back on after every use. I use both the 470 and 50 ml, but I like the small ones better. Out of date glue can be a big problem, so check the date on the glue! I do not use if it's out of date.

From contributor E:
I agree with the other comments, except they never said anything about roughing the seam with 80 grit sandpaper, which really adds strength for me. Also, if you don't have seam clamps, a cheap alternative is to use C clamps and bungee straps to keep an even pressure on the seam. Key to a seam for me is even pressure, denatured alcohol, scuff with sandpaper. Also use metal tape under the seam and have some support behind the seam when you glue them. I set my tops up on top of some MDF or particleboard until it's ready to build up.