Multi-Layer PVC

[matt_r]

I have a customer that wants me to glue multiple sheets of PVC (sintra) together, and then cut them. This is an outdoor application.
So, what would any of you recommend for gluing these sheets together?

Thanks

-Matt

[billp]

Matt,
You might try "Roo Glue", in particular their "Clear" version of the product.
http://www.rooglue.com/index.html
They state on their site that it CAN be used with PVC...

[matt_r]

Excellent thought Bill! I even have a bottle of it in the shop. Works great on Melamine. I'm only wondering if it will hold up outside. It says its waterproof upon drying, but no other claims of weatherability beyond that.\

I may try some scrap pieces first.

Thanks,

Matt

[billp]

Matt,
If for some reason there's any doubt about it's outside strength, you can probably just scuff up the surface with something like an 80 grit sandpaper, and roll on a thin coat of epoxy as well...

[Brady Watson]

You can also experiment with clear PVC cement. The stuff is amazing & is used in outdoor PVC electrical conduit & pipes. If not, any good laminating epoxy will work as long as you scuff the inner layers with 60 grit paper to give them tooth.

-Brady

[btk]

Matt,
I use Bond & Fill PVC Glue. It dries white and is
machineable/sandable and specifically formulated for PVC Trim used outside.
http://www.bondfill.com/

Brian

[robtown]

In did this a few years back. We tried many things and failed before I broke down and called the Sintra help line. An engineer there turned me on to the solution, MEK. Slosh it on and slap it down quick, then apply pressure (sandbags). We ended up using a watering can and cutting the sections to be glued up down to 24"x24" pcs to make it all manageable...

What we found with all other glue/solvent weld solutions was that it became a brittle section (the glue line) that easily cracked and broke away from the piece below it. MEK actually welded the PVC together. Try it, it works!

[gerald_d]

How PVC (cloth) boats are sometimes made:
http://www.yostwerks.com/Skin3.html

[jseiler]

I've never used this before, but the other products they make are pretty good.

http://www.gorillapvc.com/index.shtml

John

[rookie432]

Clear PVC Glue is the only sure thing in this application. I sell this stuff everyday along with the pvc conduit. It actually chemically reacts with the pvc to weld the material together. No scuffing , no buffing , however it doesn't have a very long open air working time but it is cheap and completely weatherproof and chemical resistant.

Bill

[matt_r]

This is why this forum is so great. What a great knowledge base!

FYI on the Roo Glue. No Go. I glued up some scraps last night. While the edges cured, the interior did not. After drying over night, I was able to pull the pieces apart, and found the interior still wet.

I think the clear PVC glue may be the way to go on this. It makes sense. Although, the MEK sounds interesting too.

Thanks for all the input.

-matt

[robtown]

Like I said what we found out with the standard PVC glue and the Weld-On that was recommended (I don't recall which number)was that the glue lines did in fact melt together, but they became brittle as well, causing the glue lines to fail and we had a large percentage of failed parts. Try a sample with straight MEK, that's the main ingredient in PVC cement I believe.

[matt_r]

Rob,
I was reading the link that Gerald provided, and it talked about using a combo of MEK and HH-66 vinyl cement. In the article, they said that a byproduct of the MEK was water, and that you had to wipe off the board before applying the cement. Did you see water when you applied the MEK? If so, did you remove it? How much working time do you have when you are doing this, and how much cure time do you need? Sounds like you need to move quickly, and apply pressure quickly.

Thanks,

-matt

[robtown]

No water issues.

What we did was cut down our sheets to 24"x24", wiped off a side laying flat, and flooded a piece with MEK and slapped another one on top quickly with pressure (Iron Grate and sand bags) after about 10 minutes we'd remove the grate/sand and do another on top (we needed 3 layers 1/4" pvc white-yellow-white). Gotta work fast after pouring it out cause it evaporates quick. after applying pressure it only takes about 10 minutes for it to set up enough to take the pressure off. Give it a couple hours before cutting.

The MEK obviously comes out all 4 sides (we did this in the paint booth) and on some of the sheets the outermost edges were kind of messy (had to cut off an inch or so). But when cutting the shapes (6000) this method yielded the most reliable cutting stock.

[Brady Watson]

You can also use Polyurethane-based glues like Gorilla glue...but you have to scuff the pvc a little with 60 grit to give it some bite. You do get some expansion, so spread the glue evenly. I still think that epoxy resin (like you get at the boat store) is the best bet.

-B

[btk]

Matt,
If you decide to go with the clear PVC Cement,
AZEK makes a version that is formulated the same as regular PVC Cement (that you would buy for pvc plumbing), however it has a longer set time.
This might give you some more flexibility considering that PVC cement sets up so quickly.
One drawback is that it is a bit more expenisive than regular PVC cemeent

Brian

[gerald_d]

For a solvent glue to "dry", the solvent must get out of the joint - that is what drying means. The solvent has to diffuse into the base material if it cannot evaporate into the air. Therefore the base materials must be "soluble" with the solvent to some extent, ie. the material must be able to "absorb" the solvent.

If the glue has water as its solvent, it won't dry between two sheets of water-resistant plastic.

If too much glue (and solvent) are put in the joint, the base materials can't absorb all of it and the joint does not "dry"

If too little glue (and solvent) is applied, the solvent escapes to the atmosphere before it can bite (soak) into the base material.

It has a lot to do with luck......

[paul_z]

If I remember correctly, gorilla glue requires water to set up. If it doesn't get water it stays liquid just as if it were stored in it's container.

Here's a quote - "You'll get the best results with Gorilla Glue™ when the moisture content of material is from 8% to 25%. Below 8%, spritz or dampen non-glue surface with water."

Perhaps one needs to sand the joint and then wet it just before applying the glue.

[matt_r]

A little update and further information.

I ended up going with standard plumbing PVC cement. I tried some scrap pieces with standard MEK and pressure, and it seemed to work. And if I had to do it again, I would probably take that route.

In my case, I neglected to mention a couple of factors.

1)When I made my initial post, I had already cut the letters.

2) I had had some problems with this particular piece of Sintra warping (black sintra in the back of a short bed pickup truck bows like crazy in the hot sun - lessoned learned there!).

I had tried to flatten out the board prior to cutting, but the parts still had some warping. So when I delivered initally to the customer - he looked at me as if I was nuts. I figured he'd just glue them with gorilla glue and clamp them and it would be all done. So, he calls me back up, says the parts are totally unacceptable, and they won't work. Of coarse, he's trying to put them together with double stick tape, and it wasn't exactly sucking the bow out of the parts. So, I take them back, and write a post on SB forum. SB Forum rocks, and I get all sorts of ideas.
In the end, due to not wanting the MEK to spill over the sides of the letters, I went with the standard plumbing cement AND SCREWS! I had to put 3 layers of 1/2" together, and was able to countersink and use FH screws from the back, and seal the heads up with Silicone. Needless to say they are very flat now. The only kicker was lining up the layers so all edges matched. Very tough to do. If I had to do it again, I would bond the PVC together first, then I would cut out the parts.

Anyway, thanks for all of the input. I believe that this helps further the knowledge base on this forum and I appreciate that.

-Matt

PS, what Gerald said is true, and its why the Roo Glue never cured (dried). The Sintra has a surface that is too impervious and does not allow for the carrier (alchohol - I believe) to evarporate, and lets no oxygen in. Hence, only the glue around the edges dried and the stuff in the middle was still wet after 24 hours.

[jhicks]

Matt, Interesting issue and results. Not sure why 3 layers for a total 1.5" needed to be 3 colors BUT just in case you didn't explore it. The color cores and those material types IF their colors work are quick, good cuts, and no finish time.
If you didnt consider them, it might be something of interest for next time this comes up.

[yostwerks]

Rob Williams wrote:
>What we found with all other glue/solvent weld solutions was that it became a brittle section (the glue line) that easily cracked and broke away from the piece below it. MEK actually welded the PVC together.

Thanks Rob....I'll try the MEK only weld.

Regarding your gluing line failure comments above....

I've used HH-66 vinyl cement for the construction of PVC kayak skins for many years. These skins are overlapped at the deck to hull connection along the entire length of the boat ( up to about 18ft or so). In addition, PVC deck rigging, carry straps, coaming, etc. are also glued using HH-66.

The cement does not get brittle over time as it is quite flexible in not only warm weather, but also in cold conditions. I've never experienced a glue line failure in the 12 or so folding kayaks I've built, nor have any failures been reported to me in the over 100 homebuilt boats constructed from my builders manual, many subject to salt water usage. A glue failure is certainly possible, but if the correct procedures are followed, no failures should occur. There is no welding or sewing on my boat skins vs commercial folding kayak skins.

I use MEK, wiped on lightly, to "prep" the surfaces to be glued. All "moisture" that is generated must be allowed to dry before gluing. I use a 1000 watt heat gun held several inches away and kept moving to speed up this process and to insure that the vinyl doesn't overheat.

Next, 2 or 3 coats of HH-66, thinned about 10% with Acetone, are applied. Each coat is allowed to dry to the touch before the next coat is applied.

The secret to the success of using HH-66 is in allowing the two surfaces to be completely dry before gluing them together. Otherwise, you have what amounts to a contact cement, and you can imagine the mess you would have with an 18ft glue joint. Instead, by allowing the cement to dry completely ( heat assisted) you have all the time necessary to position the deck ( overlap) over the hull along it's length at the gunwales before taping it down and then applying heat and hand pressure to reactivate and bond the two surfaces.

HH-66 provides such a secure bond that in testing to failure, the Vinyl will delaminate from the polyester core before the cement will fail. In fact, I have built some experimental inflatable kayaks using one continuous section of PVC with an overlap that is glued onto itself to form the sponsons. A raft valve is used to fill the sponsons and they will hold the pressure needed to inflate with no loss of air.

The Link below shows a two chamber sponson that is defined by nothing other than a 1" wide HH-66 seam between the sponsons and at the stems ( bow and stern). This is a very simple process and within the capability of inexperienced builders. The second link is for a PVC skinned / aluminum stringers / and plastic ( HDPE) cross sections folding kayak with no sponsons ( Sea Rover) glued with HH-66 cement ( no sewing) .

http://www.yostwerks.com/LacarPaddle3.html - PVC inflatable

http://www.yostwerks.com/SeaRover0a.html - Sea Rover folding kayak

To answer the original question regarding creating a several layer PVC section, I've done this when adding rub strips that are often made of several layters of glued PVC.

In addition, I've been experimenting with one fairly heavy coat of unthinned HH-66 to glue PVC and the results have been favorable. In fact, I do all of my repair patches that way with never a failure of the patch to stay in place. However, I have found that it is best to "prep" with MEK to remove the film that is present on the PVC and to "dull" the one side of the PVC that has a gloss finish. ( Coverlight Select 18oz.) The Acetone thinned cement is easier to apply and creates a smoother glue surface.

I feel obliged to mention that this is a hobby, not a business, with all designs and building instructioins free to anyone interested in building a folding kayak.

http://www.yostwerks.com - Folding Kayak Builders Manual

Best Regards,

Tom

[Brady Watson]

Hey Tom,
Pretty cool boat!

-Brady

[knight_toolworks]

I use a lot of gorilla glue on wood and I have tried it on other surfaces and it is nothing fantastic. for the most part I like e6000 a thin silicone adhisive. it sticks to about anything very well. but it takes a long time to cure where it can't get much air. so large surfaces would be a real pain. but smaller parts would be great.

[triptix3]

wow. what a wealth of information. I am using a vinyl material called 'Vintex' (made in Canada) to make a tent cover. THe spec sheet that Vintex sent me doesn't mention this cement for gluing, although it did note that seams done with loctite or some other glue delaminated rather than fail at the glue joint (tho it doesn't say under what conditions). The sales guy suggested I buy some expensive vinyl welding equipment. (NOT!)

I'm sure that anything that works for a kayak is gonna work for a tent-cabin (wood frame/vinyl cover).

What do you think?

[superior]

Another method is to use IPS's Weld-On glues. I use them for gluing plex, acrylics, PVC, etc. I use the #16, which is thickened, to glue the PVC. It also has a longer "open" time. I just run several beads on both pieces of materail, mate them together, and slide them around, face to face, until the glue is somewhat evenly spread. Lay on a flat surface, lay some heavy flat objects on them, let dry, and you are good to go. If there are some tiny holes on the edges, use the #11, which is water thin, apply and clamp. The glue actually "welds" the object together. This stuff is available at sign supplers, plastic fabricators, or other such distributors. I have used this on several outdoor products, and have no problems with it. One funeral home sign has been up for almost seven years. I guess it works, huh.
Doug