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Thread: Contact Cement Failures. HELP!!!

  1. #1

    Contact Cement Failures. HELP!!!

    I'm using DAP Weldwood contact cement (the original flammable stuff that will make you dizzy) to glue some Formica laminate to pine (lining a storm window sill).

    Here's what I'm doing:
    I'm coating the wood and letting it dry 10 minutes. The wood proceeds to drink this up and leaves a dry slick surface as if I did nothing.
    I add a 2nd and 3rd coat just like the first. I also now add a coat to the laminate. Now the wood looks sealed and after 5 minutes feels tacky. All seems well so I then proceed to stick the laminate to the wood.

    After a day, it pops loose in several spots. I can re-press it and it'll stay for a second then comes loose again.

    Any ideas on what could be wrong?


  2. #2
    I don’t see your location noted. But the stuff doesn’t work well in the cold , and really isn’t a permanent type adhesive. Inside it usually
    lasts until your interior decorator tells you to get rid of it.

  3. #3
    Quote Originally Posted by Mel Fulks View Post
    I donít see your location noted. But the stuff doesnít work well in the cold , and really isnít a permanent type adhesive. Inside it usually
    lasts until your interior decorator tells you to get rid of it.
    It's in the 50s in Missouri recently. Isn't this stuff used for counter tops?

  4. #4
    Too cold , I think you need at least 70. But please read the directions.

  5. #5
    Iíve used that to laminate Formica to plywood for an aquarium cabinet. Following the directions, the bond was definitely permanent and even after 8 years would be impossible to remove. I suspect it may be a combination of temperature along with the pine soaking it up. When I did it both the plywood and the Formica had a film on them that held really tightly when pressed together and once pressed together you couldnít pull it back up even if you wanted to adjust it. You may need to first seal the pine so you can get that tacky film surface, but Iíll wait for others to suggest what to use. Are you also waiting long enough for the surfaces to become dry before pressing them together? If I recall it needed more than 5 minutes.
    Last edited by Austin Perera; 03-03-2021 at 8:45 PM.

  6. #6
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    I have used both solvent based ( as in this one ) and water based and have done a LOT of laminating but on particle board for store fixtures and counter tops. I have never laminated pine but I can take a stab at your issue. Pine has a lot of natural resins some you can see on the surface but at times, depending on the board, there could be resin " pockets " below the surface. You will also see resin, some call it pitch around knots. I'm only guessing but the fact that the contact cement is solvent based is possibly diluting the resins in the board preventing adhesion.

  7. #7
    Neither piece should feel "tacky." It needs more time. If everything else fails, read the directions. Also are you applying enough pressure to make the bond?

  8. #8
    Years ago I worked in a cabinet shop that made fixtures for beauty shops, and about 90 percent of what we made was with plastic laminate. The above advice is right on. Contact cement needs a warm environment. Also, I think you need a longer open time - maybe 45 minutes or so before sticking the laminate to the sub straight.



    t

  9. #9
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    What Bruce said. If it's still tacky, it's not dry enough. The glue should feel completely dry to a light touch. in dealing with the differing surfaces, you should put an initial coat on the wood, let it dry, then apply a coat to both surfaces. More coats will give a weaker bond as well as an unsightly, thick glue line at the edges. I've never applied more than 2 coats.

  10. #10
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    The instructions say to wait 15 minutes before applying additional coatings of cement. I suspect that Bruce is correct that the cement you applied wasn't dry long enough to produce a good bond. You had about 2 hours of open time to work with after the final coating. Tacky surfaces shouldn't be placed together. If adhesive comes off on your finger when you press against it it is still too wet to bond.
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  11. #11
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    Agree with previous comments. Either too cold and/or you didn’t wait long enough and/or you had a bad can. I have had a bad can of this stuff. It doesn’t turn over on store shelves as rapidly as some products.

    To use it successfully I often wait 30-40 minutes in a warm dry environment before sticking the pieces together.
    Last edited by Dan Gaylin; 03-03-2021 at 10:58 PM.

  12. #12
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    Are you just sticking it on or rolling it hard with a J-roller

  13. #13
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    You're not letting it dry enough. "Tacky" is still too wet.

  14. #14
    Excellent and thanks. I had read on the can that a knuckle should come off dry but a little sticky (at least I thought it said a little tacky I'll read it again). I watched several videos that show it as almost dry before sticking.

    I think temp and humidity were part of my problem. I'm lining the inside of a storm window and there was both cold and humidity taking effect by the end of the day. The earlier work did hold up better. Maybe summer time full heat on a dry week is a better bet. I will practice a little more on scrap.

    thanks again for the tips!!

  15. #15
    +1 on the dry not tacky advise. You want it completely gassed off before sticking. Remember, it's not glue. It's more akin to making masking tape. You wouldn't expect tape to stick to a wetted surface. Temperature and humidity shouldn't really cause an issue as long as we're not talking extremes.

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