Correcting High Spots on Laminate Tops

Tiny bits of debris left on the matching surfaces during glue-up can cause high spots to show on a laminate top. Here are tips on how to prevent that, and how to fix it when it does happen. March 29, 2006

I just finished laminating some custom work surfaces and noticed something telegraphing through the laminate. My guess is some dust or debris got caught under it. I re-cut the tops, vacuumed and used a tack cloth on the woodcore and laminate. I even checked each piece before adhering the laminate. Sure enough, the same thing happened again. I used Wilsonart laminate, and Fastbond 30-nf glue. Anybody have any tips?

Forum Responses
(Laminate and Solid Surfacing Forum)
From contributor A:
What are you using for rods and are they clean?

From contributor B:
I would not use a tack cloth. Use compressed air and run your hand over the pieces as you blow them off. Being absolutely clean is the key. If you have several pieces to glue do not rout any parts until all the pieces are glued.

From the original questioner:
As for the rods, I'm using small diameter dowels, making sure that they are clean before using. I don't usually use the tack cloth, and it never occurred to me to use compressed air.

From contributor C:
Always blow the area off before applying the cement. I use nf-30 also. As you slide the dowels out from under the laminate if there is too much pressure between the lam and the substrate, the cement will ball up as you pull the rods out. Also, if you have even the tiniest amount of cement on the rods they will bond and ball up as you pull them out. Make sure you aren't putting the rods down too soon.

From contributor D:
Once you're sure the glue has dried on the laminate and substrate, take a cabinet scraper and gently drag it over each glued surface. At the end of each stroke, wipe the edge of the scraper between your fingers to remove fragments that have accumulated. Also as others have said, look for little rolled up balls of glue. When I do lay-ups, I typically will wipe each rod with my hand or tap it on a solid surface to remove any dust or glue that occasionally accumulates on them. After placing the rods on the substrate and positioning the laminate on top of the rods, I check for proper alignment of the laminate to the substrate. At this point, I will remove one or two rods from the center of the panel, press down on the laminate to initiate the bond and then lift the laminate on one side of the adhered section and lift the rods off of the substrate. Then, I visually inspect the surfaces and press them into place. Next, do the same with the remaining laminate and sticks.
If, after adhering the laminate to the substrate, you see or feel bumps, all is not lost. First, circle the bumps on the piece of laminate, so they'll be easy to locate. Next, use whatever thinner is recommended for the contact cement you’re using and delaminate the laminiate from the substrate. I use acetone for water based cements and lacquer thinner for flammables. As you peel the lam back, stop just after passing the point where the bumps are located. No need to run a river of thinner in there either, just enough to break the bond. At this time you should be able to locate the item that is causing the bump. You can now remove the item and put a clean prop of your choosing between the lam and the substrate and allow the thinner to flash off or evaporate. Now you can either dab a small amount of contact cement on the spot where the item was, or as many do, just remove the prop, make a visual and hand check of the surfaces to ensure cleanliness, and put the laminate back in place. Roll it out and inspect the surface for bumps. This should save you a lot of time and money by not having to remake a product that could otherwise be repaired.

If you find yourself in a situation, where delaminating is not an option, try this. If the product is a countertop or something that will only be seen from the top and not the underside, locate the bump and take accurate measurements of the location of the bump. Transfer these coordinates to the opposite side of surface and with a plunge router, if available, and set the depth to the thickness of the core and backer if any was used. Now, holding the plunge router over that coordinate, remove as much of the core as needed to get to a point where the bit has just barely broken thru the core material or is slightly short of that point. If you pull up short of the laminate you can gently scrape away the remainder of the core and low and behold, you should find the particle causing the bump. Then feel the show side of the laminate to be sure the bump is gone. If you used, for example, a 1/2" diameter router bit and didn't wander much when plunging the bump excavation hole, you can simply fit a dowel rod with some glue on it into the hole to support that portion of the laminate. Try to avoid the temptation to use bondo to fill the hole. Since it tends to shrink, you'll find yourself with a depression where the bump used to be.

From contributor E:
If you use solvent instead of thinner, after a couple minutes you can re-stick. Thinner should dry for hours. When others say look at your surfaces, they mean kneel down and look straight across the horizontal plane. If there is anything there big enough to show through, it will definitely be seen. Also if you are using standard grade, as you should be, circle the spot, put a piece of laminate over the spot and tap it down with a hammer. This will almost always work unless your problem is glue bumps. One other trick, if the problem is near the edge, is to take a piece of metal banding and cut a hook on the end. Belt sand the end till it's thin and sharp, then you can slide under p-lam and pull out the piece. We call them chip finders - hang it up and keep for next time if there is one.

From the original questioner:
There certainly are a lot of good tricks and tips to help flatten that learning curve. I still have one of the reject tops to play with. I am going to try the plunge router tip and see how that works out.

From contributor F:
Check your laminate! I did a job several months ago and found dozens of lumps in the sheet. They radiated to both sides of the laminate. If there were only a couple, I might have missed them. This taught me to always inspect in direct light, and to feel for imperfections.

From contributor D:
To contributor F: Out of curiosity, what brand name of laminate was that?

From contributor F:
To contributor D: It was a Formica brand. The supplier gave me credit for the sheet, and replaced it no charge, but I was out my time.

The comments below were added after this Forum discussion was archived as a Knowledge Base article (add your comment).

Comment from contributor R:
I own a medium sized shop making about 100 to 120 LF of laminated tops per day. A few things we do are:

1. Have a separate area for fabrication and gluing.

2. Set work flow to minimize the chance of something getting into our glue. Fabricate, sand, spray glue, lay up laminate, trim, finish file and start the process over.

3. If something should get on the top and not removed before the laminate is laid up, we have "bugger-pickers" made out of a piece of metal pallet banding with a hook cut into one end, then sanded as thin as possible without giving up strength. To use, pour lacquer thinner on the metal and work in between the laminate and the wood, directing it at the "bugger" under the laminate. Once you are in as far as you need to be, work the hook around to grab the "bugger" and pull it out. Allow the thinner the dry up and roll over the area again to assure laminate bonds with wood. It works great and saves a ton of time and material. Be careful to push straight in and pull straight out as any lifting on the "bugger-picker" may crack the laminate.

4. If a mistake happens like someone trims laminate on one top right next to another that has glue applied, but laminate has not been laid up yet and it gets covered in small laminate chips, we use scrapers made of (2) left over pieces of edging glued back-to-back. These are about 1 3/4" tall and about 8" long. They work great for scraping off any debris that landed on the glue. Just keep going over till the tops feel nice and smooth, making sure to wipe off the scraper after each pass over the glued top.