Bonding plastic to wood

[Scott Shepherd]

I have some signs I've made before and now I have a large order for them. They are made from MDF and IPI/Rowmark type plastics. It's 1/2" of MDF on the back, then a sheet of plastic, then a 1/4" sheet of MDF, then another piece of plastic, all in some odd shapes.

In the past, I have used Loctite Contact Cement. I always thought it did great until I had a batch of them sitting out for a couple of weeks (the customer delayed shipment after I made them). I noticed something odd, went to take a closer look and one of them had come apart. The plastic had popped off of the MDF. I checked all the others and they seemed tight. I couldn't pull them off when trying. However, it freaked me out enough to know that I don't want that happening once they are hung.

Right now I have an order for about 25 of them, and I wanted to use something different, but I can't find anything that says it bonds smooth plastic to wood in a hurry. Many products do it, but they require clamping and 30 minutes to 2 hours of drying time under pressure.

I can't clamp the items, as I don't have 75 clamps and I don't have 5 days to watch each one sit clamped at each step for hours. Anyone know of a good product that will bond these two items quickly. Ideally, I'd like for it to work just like contact cement, where you place the item where you want it and it's stuck, then you move to the next one.

[Brian Robison]

Hi Scott,
I went to Sloans Woodshop the other day, they sell a glue that is supposed to be just for this. I bought a bottle but I haven't used it enough yet. I glued a plastic part to wood on my guitar but it's not under and real stress.
http://www.sloanswoodshop.com/misc_.htm

[Richard Rumancik]

Did you get the Loctite product at a retail store? Usually Loctite has industrial reps that will come around and assist in selecting a suitable product. If you look in the yellow pages you might find the contact. They have a lot of good adhesives. Also check out 3M industrial adhesives. Some of the products might be a bit expensive but are generally high quality products. Many of these are not sold at the hardware store.

[Dave Jones]

It's possible that your one piece had some oil or dirt on the plastic which prevented a good bond.

One thing that may help, with whatever glue you use, is to take some coarse sandpaper and rough up the back of the plastic and then clean the sanding dust off of it. Glue always grabs a rough surface better than a perfectly smooth one.

[Bruce Volden]

Scott,

Have you ever used RTV (room temp. vulcanized)? I have not used it for your application but could not imagine it failing. You can buy it in the caulking dept. (paint?) of the BORGs. It is a little more expensive, but hey, whats peace of mind go for nowdays? :D :D

Bruce

[Scott Shepherd]

Thanks guys! I hunted 3 bottles of the one Brian mentioned down. Holy crap! It doesn't stick like contact cement, but I stuck a piece of plastic to MDF and came back about 30 minutes later and tried with all my might to pull it off the MDF. It didn't even think about budging.

As for the Loctite product, I called the MFG and they said only two places carry it, Wal-Mart and Target. Wal-Mart, and I have been to about 6 of them looking for it, no longer stock it, and Target gives it 3 cans worth on the shelf, and most of the time, I am able to get 1 or 2 cans from there, and I end up driving all over town to all the other Targets, just to end up with 8 small cans.

I really like how "stuck" this new stuff is. I'm going to let it dry for another few minutes and then try and pry it off with a screwdriver.

I'll report back.

[Scott Shepherd]

Well, you certainly won't have to worry about that ever coming off. I tried to pry it off with a screwdriver and I couldn't even get an edge to come up to get the screwdriver under.

Good find Brian, thanks for sharing it.

One favorite thing I like is that it says "Use sparingly" on the bottle. A little goes a long way.

Ace Hardware seem to carry it.

[Mike Null]

It also has a long shelf life.

[Brian Robison]

Glad to know it works, I hadn't put it to the test yet.
Thanks for testing:)

[Bill Cunningham]

I like the ones that say "Not tested on Animals" So, if you ever want to stick a weasel to a window, yer plum outta luck!!:D

[Dave Jones]

Are you talking about WeldBond? I got a bottle of that last year from Sloans. I figured it was just wood glue, and it works great for that. Then I saw it did all sorts of other stuff. I was amazed at how well it worked.

[Mike Null]

Dave

That's the stuff. Like you, the more I use it the more I like it.

[Doug Bergstrom]

We use a lot of different glues but for a project like that I would use 3M Double coated paper tape #410. i buy it from Johnson Plastics. Works great and will not come off. Less mess and no dry time.
Doug

[Bill Cunningham]

Are you talking about WeldBond? I got a bottle of that last year from Sloans. I figured it was just wood glue, and it works great for that. Then I saw it did all sorts of other stuff. I was amazed at how well it worked.

Weldbond works well for most stuff, but keep in mind that it's not waterproof.. If it thickens up over time, you can thin it with water.. I bought a gallon jug about 7 years ago, and I'm still using it..

[Mike Hood]

Another way to hold lots of small items down while gluing up is a vacuum press. I built mine up a few months back and surprisingly use it all the time.

You can apply incredible pressures over a very large area... with nothing but a plastig bag. :)