Author Topic: Removing contact cement from MDF?  (Read 3519 times)

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Offline Mr.Scrappy

  • Posts: 18
Removing contact cement from MDF?
« on: May 02, 2022, 01:43 PM »
Hope this is the right thread topic to post…

I recently attempted to laminate my new bench top with formica. While removing a sticker I accidentally let the formica touch where I wasn’t ready for it too ( I started in the center and rolled out to the left, that went great, when trying to do the right a bubble formed when it touched prematurely) I attempted to slowly peel it off when I snapped the formica
I walked out of the shop.

That was last week, today I spent the morning with a heat gun peeling the sheet back off. My top is MDF with hard maple wrap. What is the best way to remove the contact cement on the MDF so it’s smooth and I can attempt a new sheet? I tried 80 grit with my RO125feq, but as expected, it just spreads the glue.

I appreciate any help with this




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Offline Peter Kelly

  • Posts: 183
Re: Removing contact cement from MDF?
« Reply #1 on: May 02, 2022, 02:35 PM »
I'd just pick any broken bits of laminate off, re-roll or spray new contact cement and lay a new top sheet on using horizontal grade material. It's just a work top that's going to (hopefully) get worn anyway. 

Offline jeffinsgf

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Re: Removing contact cement from MDF?
« Reply #2 on: May 02, 2022, 03:44 PM »
Was it solvent-based or water-based contact cement? If the former, I would expect either acetone or lacquer thinner to clean it. Not sure what would cut cured water-based.

Offline Peter_C

  • Posts: 1382
Re: Removing contact cement from MDF?
« Reply #3 on: May 02, 2022, 06:19 PM »
If you can figure out the solvent that liquefies the solidified glue you may be able to move forward with the laminate install without removing the glue from the table. We do that for contact adhesives when doing drysuit repairs. Much to hard to remove the MEK based glue without damaging the substrate. MEK or Acetone are probably the most common solvents.

Offline Lincoln

  • Posts: 295
Re: Removing contact cement from MDF?
« Reply #4 on: May 02, 2022, 11:15 PM »
Make sure there are no lumps or bumps and respray the adhesive. It will re-activate it and should stick fine.
Don't try and remove with solvent, won't work.

Offline Mr.Scrappy

  • Posts: 18
Re: Removing contact cement from MDF?
« Reply #5 on: May 02, 2022, 11:21 PM »
Make sure there are no lumps or bumps and respray the adhesive. It will re-activate it and should stick fine.
This has been my concern. Not getting all the bumps out and it showing like a sore thumb when applying the Formica.

I was concerned about swelling with using acetone or paint thinner. I would pour some on a sponge, wipe on a small area and then scrape with a putty knife. It’s been a very tedious day or doing that. Still a long way to go, but it seems to work.

I appreciate the comments!


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Offline Lincoln

  • Posts: 295
Re: Removing contact cement from MDF?
« Reply #6 on: May 02, 2022, 11:26 PM »
You should be able to roll out any soft glue bumps. I'd only be concerned about pieces of broken laminate stuck in the glue.
Did you have sticks under the laminate when you laid it?

Offline Mr.Scrappy

  • Posts: 18
Re: Removing contact cement from MDF?
« Reply #7 on: May 02, 2022, 11:29 PM »
You should be able to roll out any soft glue bumps. I'd only be concerned about pieces of broken laminate stuck in the glue.
Did you have sticks under the laminate when you laid it?
I’ll try rolling it out, hadn’t considered that thank you.

Yes had stickers, as I was pulling one out.


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Offline Crazyraceguy

  • Posts: 2086
Re: Removing contact cement from MDF?
« Reply #8 on: May 07, 2022, 07:10 PM »
Sadly, once peeled, the chances of it laying back perfectly have diminished greatly. The color/finish/texture of the laminate plays a big role in how visible it will be. Darker and more shiny are the worst, along with solid colors. Patterns or wood grains and flat or matte finishes hide problems in the substrate. "Soft" bumps can sometimes be minimized by concentrating on rolling them out with a steel roller, not a rubber J-roller.
With "hard" bumps, like a chip of laminate, rolling can actually make it worse.
The thickness of the laminate makes a difference too. "Technically" there are 3 grades (thicknesses) of laminate, though the original "standard" grade is getting harder obtain, at least around here. Most of what is available for horizontal applications is what is known as "Post Form" grade. It is thinner than the old standard, making it far easier to bend. The tops you see in home centers with the integral backsplash and rolled front edge are made with this and it has kind of replaced the old thick stuff.
Then there is a "vertical" grade, quite a bit thinner, but not nearly as durable. It is fine for cabinet sides and doors, it just won't stand up to being "used" on a countertop very well.
The thin stuff is the worst about showing defects underneath, but it is most likely that you have the middle thickness material.

In the future, if this ever happens again(or for anyone else looking to do this) first, don't panic. You absolutely can/will make it worse. This all assumes a solvent-based contact cement BTW.
Since you had it partly/mostly stuck (in the correct position) the only real problem is the rogue stuck place. That can easily be peeled up buy applying some lacquer thinner to only the stuck area. What you need to do to get it there depends upon how it is stuck, but a squirt bottle works well in most cases. If you need to tilt the piece and pour it under the nearest gap, that works too. The main thing is to not put too much pressure on it. The pressure actually transfers around and will cause it to push down somewhere else and get more of it stuck as you peel on the other end. When you get it un-stuck, pull it back over the permanently stuck part and allow all of it to dry some more. It should take very little pressure when pulling it up, this allows the glue to melt and release, rather than forcing it apart. That tears the glue and you will get bumps from it later. After the new solvent has dried a while, give it a very light re-spray of contact, and proceed in rolling the sheet out. Once the main part of it is stuck and you have the rest rolled up like a hinge, it will lay down straight. It has no choice as long as you allow it to roll out and not touch ahead of the rest.
This same technique does work if you are stuck crooked and have to remove the whole thing too. It just takes more solvent (lacquer thinner). Stuck is not ruined, cracked is.
I have been doing this a long time, have stuck thousands of sheets of this stuff, and it still happens once in a while. Whether it is a chunk of dust in the air or a piece that was cut too close to size and I missed when sticking, it happens. I have also had people bump into and crack the overhanging part, requiring a peel and re-stick. Trim the overhang as quickly as possible too. The sooner you peel it the better, the bond does get stronger over time.
Long story, but it could have saved this job. I hope it does for the next guy.
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Offline Mr.Scrappy

  • Posts: 18
Re: Removing contact cement from MDF?
« Reply #9 on: May 07, 2022, 08:42 PM »
Sadly, once peeled, the chances of it laying back perfectly have diminished greatly. The color/finish/texture of the laminate plays a big role in how visible it will be. Darker and more shiny are the worst, along with solid colors. Patterns or wood grains and flat or matte finishes hide problems in the substrate. "Soft" bumps can sometimes be minimized by concentrating on rolling them out with a steel roller, not a rubber J-roller.
With "hard" bumps, like a chip of laminate, rolling can actually make it worse.
The thickness of the laminate makes a difference too. "Technically" there are 3 grades (thicknesses) of laminate, though the original "standard" grade is getting harder obtain, at least around here. Most of what is available for horizontal applications is what is known as "Post Form" grade. It is thinner than the old standard, making it far easier to bend. The tops you see in home centers with the integral backsplash and rolled front edge are made with this and it has kind of replaced the old thick stuff.
Then there is a "vertical" grade, quite a bit thinner, but not nearly as durable. It is fine for cabinet sides and doors, it just won't stand up to being "used" on a countertop very well.
The thin stuff is the worst about showing defects underneath, but it is most likely that you have the middle thickness material.

In the future, if this ever happens again(or for anyone else looking to do this) first, don't panic. You absolutely can/will make it worse. This all assumes a solvent-based contact cement BTW.
Since you had it partly/mostly stuck (in the correct position) the only real problem is the rogue stuck place. That can easily be peeled up buy applying some lacquer thinner to only the stuck area. What you need to do to get it there depends upon how it is stuck, but a squirt bottle works well in most cases. If you need to tilt the piece and pour it under the nearest gap, that works too. The main thing is to not put too much pressure on it. The pressure actually transfers around and will cause it to push down somewhere else and get more of it stuck as you peel on the other end. When you get it un-stuck, pull it back over the permanently stuck part and allow all of it to dry some more. It should take very little pressure when pulling it up, this allows the glue to melt and release, rather than forcing it apart. That tears the glue and you will get bumps from it later. After the new solvent has dried a while, give it a very light re-spray of contact, and proceed in rolling the sheet out. Once the main part of it is stuck and you have the rest rolled up like a hinge, it will lay down straight. It has no choice as long as you allow it to roll out and not touch ahead of the rest.
This same technique does work if you are stuck crooked and have to remove the whole thing too. It just takes more solvent (lacquer thinner). Stuck is not ruined, cracked is.
I have been doing this a long time, have stuck thousands of sheets of this stuff, and it still happens once in a while. Whether it is a chunk of dust in the air or a piece that was cut too close to size and I missed when sticking, it happens. I have also had people bump into and crack the overhanging part, requiring a peel and re-stick. Trim the overhang as quickly as possible too. The sooner you peel it the better, the bond does get stronger over time.
Long story, but it could have saved this job. I hope it does for the next guy.
Great write up crazy guy! Really appreciate the knowledge, I’m sure it will help me in the future


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Offline Crazyraceguy

  • Posts: 2086
Re: Removing contact cement from MDF?
« Reply #10 on: May 08, 2022, 10:59 AM »
It's just too bad that it was too late for this particular job.
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Offline Mr.Scrappy

  • Posts: 18
Re: Removing contact cement from MDF?
« Reply #11 on: May 11, 2022, 10:48 PM »
Just a little follow up on this.. finally had another free day to work in the shop. Again I went over the entire top with lots of paint thinner and a puffy knife trying to get as much of the contact cement as possible. I then once it was dry, hit it with 80 grit, this would basically rub the high spots down and distribute the adhesive more evenly.

I finally went ahead and tried it again, fully expected to have plenty of visible bumps in the top after I rolled it from the leftover glue. To my surprise, I think I only have one small bump that I can see, so I’m very pleased with the results.

(Please forgive the mess in the shop, hobbyist, father of two kids 5 and under, and a farm to keep up)
 

 




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Offline Peter_C

  • Posts: 1382
Re: Removing contact cement from MDF?
« Reply #12 on: May 12, 2022, 12:24 AM »
That is a great work bench! I like the top color too and I keep wavering between red and grey for my tablesaw top when I remake it.

Curious what type of farming you do? We have a certified tree farm (FSC), with a smaller home farm with rotating crops like wheat. We have people who handle the day to day operations for us by crop sharing and using a Forrester to manage logging operations. Studying up on "Differed harvest carbon credits" as we don't harvest but every few years per our stewardship plan.

You could try to apply heat to the bump, and see if it will go flatter. Might take a few minutes applying heat in constant motion so as not to damage the laminate, then lots of pressure with the roller. Heat softens the glue, but it will take a little while to gently heat the area. 

Offline Packard

  • Posts: 1685
Re: Removing contact cement from MDF?
« Reply #13 on: May 12, 2022, 08:49 AM »
I looked up the MSDS sheet on contact cement (DAP) and it appears that acetone is a primary solvent. 

https://www.buildsite.com/pdf/dap/DAP-WELDWOOD-Original-Contact-Cement-SDS-1875533.pdf

They list: Distillates (petroleum), light distillate hydrotreating process, low-boiling

A quick search shows that to be acetone.

https://www.rsd.net/assets/item/1500.pdf

Based on that, I would guess that acetone will dissolve the residue.  Though I have no personal experience with this issue.


Offline Michael Kellough

  • Posts: 5724
Re: Removing contact cement from MDF?
« Reply #14 on: May 12, 2022, 10:05 AM »
I looked up the MSDS sheet on contact cement (DAP) and it appears that acetone is a primary solvent. 

https://www.buildsite.com/pdf/dap/DAP-WELDWOOD-Original-Contact-Cement-SDS-1875533.pdf

They list: Distillates (petroleum), light distillate hydrotreating process, low-boiling

A quick search shows that to be acetone.

https://www.rsd.net/assets/item/1500.pdf

Based on that, I would guess that acetone will dissolve the residue.  Though I have no personal experience with this issue.

Good detective work! Dap does sell rubber cement thinner but acetone works and is probably less hazardous.

Offline Packard

  • Posts: 1685
Re: Removing contact cement from MDF?
« Reply #15 on: May 12, 2022, 10:27 AM »
Of course he can also remove the residue mechanically (scraping, sanding, etc.) and he may have to do some of that anyway.

You would be surprised at what can telegraph through a sheet of formica.  It can have some small voids, but anything that stands proud of the surface will show in the final product.

To position a sheet of Formica, first place several long dowels on the surface sufficient to keep the Formica from contacting the surface.  Check the alignment of the Formica and the surface and then remove dowels at one end only.  Remove enough of the dowels so that the end of the sheet is nearly touching the surface.  Double check the alignment and then press down at that one end.  Then remove the remaining dowels in sequence, pressing down on the sheet as you go.  Follow up with a roller for best results. 

Because the dowels do not have any contact cement on them, they will not adhere to the sheet.  Both surfaces have to be coated with contact cement for a permanent bond.  So the dowels will not stick.

Offline rst

  • Posts: 2851
Re: Removing contact cement from MDF?
« Reply #16 on: May 12, 2022, 12:19 PM »
Back in the seventies we just slipped newspaper between the top and the Formica after both dried.  Used the same method when I did my bathroom counters.

Offline Packard

  • Posts: 1685
Re: Removing contact cement from MDF?
« Reply #17 on: May 12, 2022, 12:41 PM »
I always used dowels.  The same principle.  So whatever works.  You only have one shot at perfect alignment.

Offline Mr.Scrappy

  • Posts: 18
Re: Removing contact cement from MDF?
« Reply #18 on: May 12, 2022, 01:43 PM »
That is a great work bench! I like the top color too and I keep wavering between red and grey for my tablesaw top when I remake it.

Curious what type of farming you do? We have a certified tree farm (FSC), with a smaller home farm with rotating crops like wheat. We have people who handle the day to day operations for us by crop sharing and using a Forrester to manage logging operations. Studying up on "Differed harvest carbon credits" as we don't harvest but every few years per our stewardship plan.

You could try to apply heat to the bump, and see if it will go flatter. Might take a few minutes applying heat in constant motion so as not to damage the laminate, then lots of pressure with the roller. Heat softens the glue, but it will take a little while to gently heat the area.
Thanks Peter!

We are only on 5 acres, so we don’t grow anything. We have too many chickens (40+) goats 6, 2 horses, so there is always something to be done, cleaning stalls etc. we do sell our eggs, and we never have enough for the demand even getting 3+ dozen a day! My full time job is a corporate pilot, so I’m often on the road for days at a time. So when I get home it’s taking care of the kids, cleaning up around the farm, and then lastly is shop time.


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Offline Mr.Scrappy

  • Posts: 18
Re: Removing contact cement from MDF?
« Reply #19 on: May 12, 2022, 01:45 PM »
I looked up the MSDS sheet on contact cement (DAP) and it appears that acetone is a primary solvent. 

https://www.buildsite.com/pdf/dap/DAP-WELDWOOD-Original-Contact-Cement-SDS-1875533.pdf

They list: Distillates (petroleum), light distillate hydrotreating process, low-boiling

A quick search shows that to be acetone.

https://www.rsd.net/assets/item/1500.pdf

Based on that, I would guess that acetone will dissolve the residue.  Though I have no personal experience with this issue.
Hey Packard,

Thanks for the info, I didn’t have too much acetone on hand, so when I ran out I went with the paint thinner, and it seemed to do just as well as the acetone.


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Offline Mr.Scrappy

  • Posts: 18
Re: Removing contact cement from MDF?
« Reply #20 on: May 12, 2022, 01:47 PM »
That is a great work bench! I like the top color too and I keep wavering between red and grey for my tablesaw top when I remake it.

Curious what type of farming you do? We have a certified tree farm (FSC), with a smaller home farm with rotating crops like wheat. We have people who handle the day to day operations for us by crop sharing and using a Forrester to manage logging operations. Studying up on "Differed harvest carbon credits" as we don't harvest but every few years per our stewardship plan.

You could try to apply heat to the bump, and see if it will go flatter. Might take a few minutes applying heat in constant motion so as not to damage the laminate, then lots of pressure with the roller. Heat softens the glue, but it will take a little while to gently heat the area.

Here you can see the one bump I have in the top, I’m thinking a small piece of dust is under it, I did try heating and rolling again, to no avail. But I can certainly live with that


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Offline Mr.Scrappy

  • Posts: 18
Re: Removing contact cement from MDF?
« Reply #21 on: May 12, 2022, 01:49 PM »
Of course he can also remove the residue mechanically (scraping, sanding, etc.) and he may have to do some of that anyway.

You would be surprised at what can telegraph through a sheet of formica.  It can have some small voids, but anything that stands proud of the surface will show in the final product.

To position a sheet of Formica, first place several long dowels on the surface sufficient to keep the Formica from contacting the surface.  Check the alignment of the Formica and the surface and then remove dowels at one end only.  Remove enough of the dowels so that the end of the sheet is nearly touching the surface.  Double check the alignment and then press down at that one end.  Then remove the remaining dowels in sequence, pressing down on the sheet as you go.  Follow up with a roller for best results. 

Because the dowels do not have any contact cement on them, they will not adhere to the sheet.  Both surfaces have to be coated with contact cement for a permanent bond.  So the dowels will not stick.

I have plenty of pvc, so I used those as stickers. Made sure to wipe them clean first. Worked great


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Offline Packard

  • Posts: 1685
Re: Removing contact cement from MDF?
« Reply #22 on: May 12, 2022, 03:06 PM »


Here you can see the one bump I have in the top, I’m thinking a small piece of dust is under it, I did try heating and rolling again, to no avail. But I can certainly live with that


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You would have to give me a road map to locate the bump.  I found it surprising how small a particle would telegraph through Formica.  But a handsome bench.

As a side note, if you ever have any Formica come loose, squirt some wood glue under the loose edge and then clamp or add weight.  It will hold fine.  A vacuum cleaner can help suck the glue further inboard.  It saves the labor of removing it entirely and the cost of doing it over.  If it is just the corner, a bit of compressed air can force the glue in further. Or a flat piece of wood (like a paint mixing stick) can do the same.

Offline Mr.Scrappy

  • Posts: 18
Re: Removing contact cement from MDF?
« Reply #23 on: May 12, 2022, 03:10 PM »


Here you can see the one bump I have in the top, I’m thinking a small piece of dust is under it, I did try heating and rolling again, to no avail. But I can certainly live with that


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You would have to give me a road map to locate the bump.  I found it surprising how small a particle would telegraph through Formica.  But a handsome bench.

As a side note, if you ever have any Formica come loose, squirt some wood glue under the loose edge and then clamp or add weight.  It will hold fine.  A vacuum cleaner can help suck the glue further inboard.  It saves the labor of removing it entirely and the cost of doing it over.  If it is just the corner, a bit of compressed air can force the glue in further. Or a flat piece of wood (like a paint mixing stick) can do the same.


Here’s the bump.

Thanks for the tip! I’ll keep that in mind.


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Offline Packard

  • Posts: 1685
Re: Removing contact cement from MDF?
« Reply #24 on: May 12, 2022, 03:43 PM »
Well, erase that red arrow from the Formica and no one will know about the bump. [big grin]


Offline Crazyraceguy

  • Posts: 2086
Re: Removing contact cement from MDF?
« Reply #25 on: May 13, 2022, 07:26 PM »
The stick method works, obviously, but it has pitfalls of its own. The biggest one is the potential for introducing "junk" into the mix. Anything that is stuck to the sticks can/will end up trapped under the laminate. You also have to wait longer before sticking your parts together. Both sides have to be very dry or it is possible that the glue will stick to the sticks, at least enough to pull some away when you move them. This makes bumps too. I have also seen a guy "miss" a stick when removing them. That didn't work out well.
I only use them in very limited situations, like when there is an obstruction of some sort in the way, or up against a perpendicular surface. It usually works best to start removing the sticks from the middle and working away in each direction.
In the cabinet shop however, it is expected that this would be done "by hand". You hold the entire sheet up by one hand, guiding the edge to make contact at one corner, with about 1/4" overhang each way (side and end). Then you just "walk" that longest edge down to the other end, with that same 1/4" overhang. At that point, you just "roll" it down in a big curl. It takes some practice, but an entire 4' x 8' sheet is not that bad.


 
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