Contact cement....

[Ken Fitzgerald]

It appears getting good results with the new explosive proof contact cement is a hit or miss process.

A year or two ago I made a router table and used the water based contact cement quite successfully.

Last night I tried to glue a 5'x4' sheet of formica to a new tablesaw outfeed table I am building. It sure didn't want to adhere around the edges.

Now, how do I recover?

[Dan Hintz]

Never used "explosion-proof" (I'm assuming low- or no-VOC?). Standard install method of painting both surfaces, let dry to tack, then press together? When you say "around the edges", do you mean just the edges of a large panel aren't sticking, or the edge banding isn't sticking?

[Phil Thien]

Apparently the water-based stuff takes forever and a day to set-up to the point where you can bring mating pieces together.

I've also read that there is a big difference between brands on the water-based stuff.

I've only used the solvent-based because it has worked well for me.

[Ken Fitzgerald]

The edges of the 5' by 4' sheet aren't sticking.

The explosion proof stuff appears to have almost a "latex-like, water based carrier with much lower fumes.

After wrapping the doubled sheet of 3/4" plywood top with white oak, I used a piece jointed wood and a sharp block plane to insure the wrapped edge aligned perfectly with the plywood. I used a special adhesive roller to spread the contact cement when I applied it to both surfaces. The plywood seemed to absorb the glue so per the instructions on the can, I applied a 2nd coat. I let them dry and then applied.

It's all the same technique I used last year but for some reason, the edges of the sheet didn't seem to adhere.

I clamped some cauls to the edges overnight. I am about to go to the shop and see if anything changed.

Since the vast majority of the sheet adhered, I am at a loss about how to recover gracefully from this.

[Kent A Bathurst]

........ the new explosive proof contact cement.......

i'm almost afraid to ask................what in the heck else do you do in your shop that requires explosion-proof work surfaces?

are we going to see your photo on fbi/atf posters in the post office?

[Peter Kelly]

The edges of the 5' by 4' sheet aren't sticking.

The explosion proof stuff appears to have almost a "latex-like, water based carrier with much lower fumes.

After wrapping the doubled sheet of 3/4" plywood top with white oak, I used a piece jointed wood and a sharp block plane to insure the wrapped edge aligned perfectly with the plywood. I used a special adhesive roller to spread the contact cement when I applied it to both surfaces. The plywood seemed to absorb the glue so per the instructions on the can, I applied a 2nd coat. I let them dry and then applied.

It's all the same technique I used last year but for some reason, the edges of the sheet didn't seem to adhere.

I clamped some cauls to the edges overnight. I am about to go to the shop and see if anything changed.

Since the vast majority of the sheet adhered, I am at a loss about how to recover gracefully from this.

I'd grab a can of Wilsonart Lokweld, prop the edges up with toothpicks and spray around the perimeter of the part.

You could also try to re-activate the exhausting glue by heating with an iron.

[Ken Fitzgerald]

Kent.....I have a regular hanging natural gas furnace in my shop. I prefer to not use the regular contact cement with the combustible fumes in the winter. I enjoy using my shop.

I just came in from the shop. Maybe it was drying time? I let it dry for over an hour last night? It was glossy and tacky when my wife and I laid it on the sticks I had on top of the table.

Last night after rolling it with a J-roller, it still wasn't sticking so I clamped cauls around the edges and left it.

This morning it still didn't appear to be sticking so I trimmed the excess with a router and then rolled it again. It stuck in all but two places...one place about 4-5 inches long and one place about 2" inches long.

Peter, maybe a heat gun would reactivate the glue? If not, I will try the spray adhesive.

Thanks for the help and keep the ideas coming.

[Dan Forman]

Ken --- Don't know what to do now to correct the situation, but I do know that water based contact cement only has about a one year shelf life, and sometimes the date is not clearly marked on the container. I have had good luck with it, but have always had to buy it fresh, as it expired between projects. Hope you find a work around.

Dan

[Roy Harding]

I've found the same problem as Dan with the water based stuff (short shelf life). I've used it successfully in the past, but I've also had it fail in a similar manner which Ken describes.

I've gone back to the solvent based stuff - as much as I dislike the smell associated with it, I know it'll work. Perhaps I'm just too stubborn to replace a tried and true product with a newer one, being too lazy to ascend the associated learning curve??.

[Peter Kelly]

Peter, maybe a heat gun would reactivate the glue? If not, I will try the spray adhesive.

No, a heat gun will cook the surface so the top melamine and paper sheets will bubble and de-bond from the phenolic backer. You want a household iron to gently reactivate the glue underneath.

Lokweld or 3M 77 are probably the safest route.

[Peter Quinn]

I used the wilsonart WB contact cement for a project last fall, same issues needing non explosive cement in my basement shop so as not to level the house when boiler kicks in or poison the occupants. I did a lot of reading over on wood web and other commercial places, seems it's critical to apply the WB contact in a very thin coat, let it fully dry u till not at all tacky, air flow can help this as can warm dry air, then apply a second thin coat to the chip board/plywood side. Let that fully dry. I used a small forced hot air electric space heater to accelerate dry times to 45 minutes, ambient temp at the time was around 62 degrees. Only other thing I remember was making sure to roll from middle to edges so no air got trapped . I had one edge that didn't grab quite as well as I liked, the rest was really stuck, so I got a little more cement under the laminate with a foam brush, then warmed it with a medium house iron, seemed to do the trick. To my knowledge the bond has remained strong, it's on a top in my SIL's house, when we did the sink cutout it seemed very well bonded on the interior sections.

[Larry Edgerton]

I think you may have waited too long Ken.


I use WB but it is a commercial product that comes in a propane like tank. But the same company makes it in aerosol and I use that occasionally on small jobs or for jigs with no issues other than......

When I first switched I had some issues and after calling the company they told me I was waiting too long.

[Ken Fitzgerald]

Peter...from the middle out is how I rolled it last night. I couldn't find my heat guns ( I had 2 at one time. We used them professionally working on MR scanner magnets) so I came to the house to get my wife's iron.

Larry....the can says if you wait 3-4 hours you may need to reapply it but ...I only waited an hour. As I stated, I used it successfully last year on a router table top?

[Ken Fitzgerald]

Thank you Peter! The iron worked like a charm. Initially I didn't let it get warm enough. I was worried about damaging the formica. I removed the iron, tried rolling it with no success. I put the iron back on it and left it for another 2-3 minutes. When I removed it and rolled it that time it worked!

Thanks again for the suggestion!

[ian maybury]

Can't speak for water based contact adhesives Ken, but i seem to be noticing of late that even the aerosol solvent based variety are much more sensitive to waiting for just the right amount of time before making the bond. Leave it a bit too long and it loses all of its tack/grab. What looks like a very heavy film of adhesive as it goes on seems to end up looking very thin too, seems like the solids/solvent ratio might be significantly different to older formulations. I've ended up recoating several times.

Wouldn't be surprised if they are not using different (for maybe H&S or environmental reasons) or faster solvent (because i suspect many won't wait long enough/faster may be perceived as better) that results in a more time sensitive scenario.

My instinct would be to run a few retrospective test pieces for different drying times - to verify what was going on. Don't know what the heat does/how it re-activates the adhesive, but it might be worth testing that scenario too - there's nothing worse than having something give up the ghost long enough after the fact to be a PIA...