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Corafoam Adhesives testing

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Doug Bernhardt
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Corafoam Adhesives testing

Post by Doug Bernhardt »

Have a big job showing up in the shop and decided to run a few experiments with the adhesives that I use on-goingly with Corafoam. This job will be the first of any real scale that I have done in something other than wood and I love being certain of results. One of tests was with epoxy which is actually called "East system". The only reason I used that instead of the "Left coast variety" is that it's available with ease around here. West system is just too far a drive.

1/ was Titebond 3 to two pieces of Corafoam together. Total and complete failure. The glue only dried at the edges and the 2 nails were all that held it together.

2/ was epoxy without the 406 filler. I gave the seam/joint a couple of whacks with chisel and mallet and it popped appart with ease. The adhesive was still on both surfaces but gave only a little resistance.

3/ was polyurethane glue (gorilla and other varieties) I had Elmers as it is easy to get at the local Depot. It never actually split when I used the mallet and chisel as with the others. I eventually did get the whole thing to break but not along the joint.

Seeing that this was a pretty good test I redid in several other methods.....foam to wood and foam to foam with a couple other adhesives. PL premium and silicone as well as epoxy with the 406. Will post the results when I get home from work Monday.
joe cieslowski
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Post by joe cieslowski »

Doug,

I've been gluing up the HDU for a while. Urethane glue is the ticket, period. There can be issues tho. When used full strength and you need to remove any overage, it's tough to remove without tearing out some of the foam. Here's how i do it.

First let's say it's 1" stock. I put a small bead (a heavy 1/8") of glue along the edge about 1/3 of the way in from each edge. Soak the matching piece heavily with water....really wet. Press the two pieces together and slide em back and forth. Gently clamp. Right away, you'll see beads of glue come up. If you did it right, they will look like a string of pearls. Now pay attention and when the beads get leather hard (not sticky) skim the excess glue off with putty knife or something. Result is a nice clean, strong bond and surface. Here's a shot of 5 strips glued up in a small panel (I hate to throw away material, lol)

Image

The strips run horizontal....look carefull. I've also included a "string" of pearls from the job)

Here's the surface after sanding with 120 grit an 1 primer coat.

Image

BTW, there are always little voids to fill.......that Bondo is the trick. It dries quick and it is about as hard as the coro.....so it sands evenly!

I'll get some more pics for ya.

Here's how i apply the glue...sorry, a little outa focus. :(

Image

Here's what it looks like after the slide manuver and clamped...

Image

That was the top.......it squeezed out just a little heavier on the bottom.

After 40 minutes, (temp was 12 C) it wasn't sticky so I used a putty knife to trim off the glue....two shots, top and bottom...

Image

Image

It works great in combo with wood too. Here's a job I did with Coro that had a 3/4" thick, redwood spline (about 1 1/2" wide) glued into a dado I cut into the edges of the main rectangular part and then glued the curved part onto the top.....alined with dowels. Sweet match!

Image

Hope this shortens the curve for ya. :)











Joe
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erik winkler
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Post by erik winkler »

Joe,

I can not figure out why you used the water. Is it to slide the panels back and forth?
Won't the water on the inside be captured by the urethane(glue) and will fail the bond when freezing point ocurs?
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Doug Bernhardt
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Post by Doug Bernhardt »

Eric. That type glue only cures with moisture. Joe.....have been using that adhesive for a while and have loved the results. The clean-up I hate and always have a devil of a time getting everything to the right point (for easy clean-up much like you do) before it's Miller time or dinner. The Bondo is a terrific filler eh? Makes a mess of the sandpaper tho. Have you tried the new stuff (filler) from Elmer? Best I've ever used. Just rub on a chunck and sponge away with water. No sanding and smooth as a baby's bottom.
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Post by joe cieslowski »

Thanks for the Elmers tip.....I'll pick some up and use it for the bigger holes. I use this Bondo for the pin holes and such.
The G glue is water soluable until it drys so if you want to watch over the job for a while, the excess can be removed with a wet rag or sponge.

Joe
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joe cieslowski
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Post by joe cieslowski »

Eric,

The water becomes part of the glue and when it cures, there is no water in it to freeze and the joint itself is waterproof.

Joe
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Doug Bernhardt
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Post by Doug Bernhardt »

Joe.....the Elmers for the small stuff and Bondo fer big is the way to go. You'll like it. What do you use to get the moist glue off your hands. I do have those latex gloves but there's always some. They told me to use alcohol but you got to get it right away. Besides I have better uses for Jack Daniel's.
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Post by joe cieslowski »

Doug,

Thanks for the laugh!!! :)
I'll check out the Elmers sooner than later.

Getting the PU glue off my hands is a simple solution.....don't get any on them in the first place! :) I'll use shaped popsicle sticks to scrape away the glue when it's wet, if I have to. Catching the glue before it hardens but has lost it's "sticky" is the trick and don't apply too much at the beginning. (SOOOOOO many folks do) If I'm applying a piece onto the panel (such as an ornament) I'll blind nail it first so it won't slide around when it's wet with glue and then "clamp" with a weight.

When I use titebond, I just let it dry on my fingers and then just peal it off.

I like the tip about the Jack Daniels, I'll use it before glue-up so I really won't give a hoot about how neat it is. ;)

Joe
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Doug Bernhardt
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Post by Doug Bernhardt »

Well, Here's the scoop on the additional test pieces. Corafoam to wood with titebond3.....complete failure. Cfoam to wood with epoxy and 406 filler almost total failure. Cfoam to wood with silicone, total failure BUT Cfoam to both foam and wood (WITH PL PREMIUM) held like no tomorrow. The plywood was breaking up but the foam held tight. Used the same parameters as before and as mentioned the wood was the overlayed plywood we all use. The surprise was that the polyurethane glue didn't hold as well to the plywood as it did to itself. You know foam to foam was great....foam to ply was only so so.
Last edited by Doug Bernhardt on Mon Jan 19, 2009 9:18 pm, edited 1 time in total.
joe cieslowski
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Post by joe cieslowski »

Doug,

I have two questions...

1. Was this a shear test?

2. Did you use the PU glue full strength?

Just for clarification.

Joe
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Doug Bernhardt
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Post by Doug Bernhardt »

Whoa.....realised I omitted that this was with PL Premium. Can't believe I made that mistake and sorry.

BUT Cfoam to both foam and wood (WITH PL PREMIUM) held like no tomorrow. The plywood was breaking up but the foam held tight. Used the same parameters as before and as mentioned the wood was the overlayed plywood we all use.

Basically I glued up on Saturday and today, at the seam, I used a chisel and mallet as before and started smacking away. All the glues were full strength (straight out of the can) so to speak. I guess as far as I'm concerned I'll be using the PL to glue up mouldings and any appliques as it is easy to clean up after, holds Corafoam better to wood and just as well (as the polyurethane) with Cfoam to Cfoam. Joe.....by PV glue you mean the Titebond? It was straight from the jar also. It is also worth mentioning that when I tried the PL and Silicone I used a couple of nails (as I did with everything) and a gallon can for clamping.....much like the real day use for holding large letters onto a backgnd might be done. No clamps although I was tempted. I thought that this might be more "real world"
brian oliver
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Re: Corafoam Adhesives testing

Post by brian oliver »

I found this post in a very timely manner. I have used Gorilla Glue on a number of things bu for some reason not on HDU butt joints. This looks like it will be the perfect solution, especially when I have to sandblast thru the joint.

I have a question regarding the storage of opened Gorilla Glue bottles. Since GG will use the available water vapor to set up, how does a person keep the remaining glue in the bottle from solidifying by using the water vapor in the air that has replaced the glue that has been used out of the bottle? I have lost a lot of material this way and I hate that I have about a half bottle that "goes bad" and has to be thown out.

Any solutions?
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Re: Corafoam Adhesives testing

Post by joe cieslowski »

First, The gorilla glue seems to last on the shelf pretty long. Much longer than the cheaper stuff.......I actually had a sample from Coastal Enterprises set up before I even opened the bottle.

What I do is hold the plastic bottle upside down before I remove the cap and then squeeze out what I need and replace the cap before turning it right side up. No air gets in. I also store it upside down.

Joe
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Re: Corafoam Adhesives testing

Post by erik winkler »

joe cieslowski wrote:What I do is hold the plastic bottle upside down before I remove the cap and then squeeze out what I need and replace the cap before turning it right side up. No air gets in. I also store it upside down.
Joe
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Again a tip I can use.
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Re: Corafoam Adhesives testing

Post by Danny Baronian »

Brian,

like Joe I've found Gorilla glue to have a longer shelf life than any of the other polyurethane glues, and dispense it as he described to keep air in the container to a minimum.

Other than that, buy only what you need in a 6 to 12 month period. It cost more overall buying the smaller bottles, but you toss less if it exceeds it's useful life.

Danny
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Raymond Chapman
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Re: Corafoam Adhesives testing

Post by Raymond Chapman »

Great information. We have been using West System to glue DiBond to Corafoam with good results but would like to try the PL Premium. Have you done any tests with HDU to aluminum or DiBond? What about aluminum to aluminum?

The Lords adhesive is great, but expensive and uses up a lot of those little squiggly tips.
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Re: Corafoam Adhesives testing

Post by Doug Bernhardt »

Ray, I just tried it out on products I use and I gotta tell you....forget the West System for this material....try it out on a couple of scraps and see what you think. I actually have a little aluminum over some sort of plastic (material name unknown) and will try it out on that tomorrow..am curious myself. I've also heard there is a PL for foam products but ain't seen anything firm on that yet.
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Re: Corafoam Adhesives testing

Post by Raymond Chapman »

OK Doug....I tried some and the joints failed. What's the secret? Now, I admit I didn't read the directions, so that was probably my first mistake. How long does it take to completely cure? I let my samples set up about 18 hours, but I may have put too much adhesive on.

It did pretty good with bare corafoam, but aluminum to aluminum was the worst.
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Re: Corafoam Adhesives testing

Post by Danny Baronian »

I've found PL premium to be the next best thing to gorilla glue in a non expanding product. From product sheets, the main difference is Gorilla glue is expanding, whereas PL is not.

Aluminum to aluminum always needs to be abraded in some form. If gorilla or PL glue is used on .06 alum, use a coarse grinding wheel to give the alum some tooth. If the aluminum is dibond, puncture the faces to be bonded with a punch and or grind. When punching the face with a punch over the entire surface, using gorilla glue will expand into the punched areas giving a better grip, and will not expand between the surface as much.

As Joe said earlier, or on another glue related post, too little or too much adhesive leads to an inferior bond. But if you're gluing dibond to dibond with no surface prep other than cleaning, it's the same as gluing two pieces of glass together with elmers glue. It will have enough surface tension to hold it together for a short time, but put any shear on it and it's gone.
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Doug Bernhardt
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Re: Corafoam Adhesives testing

Post by Doug Bernhardt »

Ray.....I gotta ask which adhesive did you test? I'm guessing the epoxy and if so, the same failure happened for me. I tried some aluminum (might be dibond) and PL as mentioned and had a "reasonable" bond with the foam. I pulled it apart with a only little bit of difficulty with my hands. I had to use a mallet and chisel with plywood or foam to foam. Back to alum. I left half of it to cure over the weekend as I noticed that the PL was still not hardened on the sections I pulled apart. Will check again Monday and type in this here box then!
Danny.....I found the gorilla glue/ PU to be the next best thing to PL although I ain't tried all the variations you've mentioned.
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I have to add

Post by Doug Bernhardt »

I just wandered upstairs after making that last post and found my mind wandering over all the trials I've given to adhesives over the years. I remember lessons on gluing up planks with epoxy (which I also did for years) only to find after a short time, that we were all using these things the wrong way!! Now remember when you'd glue up some redwood and you would here popping as you took the clamps off next morning???? That was a starved joint. As soon as I started to use it as the manufacturer suggested (with the 406) I never again had a problem or any of the "popping" It was around this time I started to realize the epoxies were not the best glue/ adhesive to use. I like everyone else it seemed, relied on the toughness of west system and got lulled into the idea of what was a good bond/glue joint or whatever. Anywho......that was my long winded way of saying trial, trial, trial again!! We have to rethink the process everytime we start messing with a new material.
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Re: Corafoam Adhesives testing

Post by Danny Baronian »

Doug, that's what tripped me up in the first place when this thread started as to understanding the types of glue for your tests.

Gorilla glue is polyurethane, as is PU unless it stands for something else, as is PL Premium. They are all polyurethane based adhesives. The difference between PL Premium and gorilla is that PL Premium does not expand, and Gorilla glue is activated by moisture.

While I haven't tried it, it's possible moisture would act as an accelerator when used with PL Premium.

What is your definition of PU, and what's the name of the Elmer's wood putty you suggested?

Danny
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Re: Corafoam Adhesives testing

Post by Doug Bernhardt »

Dan, Will have to look at the putty tomorrow and get the name off the box. The PU as I'm using it means "Poly Urethane" which is Gorilla and a few other brands. I get some at the local build centre which is also an Elmers brand....again will have to look at the label to get more info. There would be places somewhere around here that I could get Gorilla and the more popular names but never really bothered. I'm still of the idea that they are "pretty much" equal. If not there can't be much difference as the Elmers PU (poly) I have is good and strong. Also.....with a magnifying glass I read the fine print on the PL premium containers and saw that it's a poly urethane of some variety as you said......I'm not a scientist but just grabbing scraps from the shop and lining them up....writing what's what on the tests and seeing what happens next morning. Then I try it again to see if small variations make a difference....you know add the 406 to the epoxy mix etc etc. By the time I've made my way through all that it's time to start the job all the testing was done for and am pretty confident in the choice. WHEWW!! all that typing...it just doesn't flow as easily as talking.
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Re: Corafoam Adhesives testing

Post by Doug Bernhardt »

A picture is a thousand words? That thar is the putty and the aluminum product peeling off the foam. The extra setting time did some good......but not enuf
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Re: Corafoam Adhesives testing

Post by Danny Baronian »

Thanks Doug, the picture will do, thank you.

I've seen that in the store, but since it was the first time I'd seen putty packaged that way, decided to check first.

Now I'll know who to blame if it doesn't work.

The glue test pictured, did you abrade the dibond, and was the HDU rinsed off well? What's surprising is how cleanly it came off the HDU, indicating a poor bond there too. Try abrading the dibond with a grinder or sanding disc w/ 60 grit, then spread a thin - 1/16" film of Gorilla glue on one surface, and mist the other, clamp well and check it in 8 hours.

Danny
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Doug Bernhardt
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Re: Corafoam Adhesives testing

Post by Doug Bernhardt »

Danno........that was my entire supply of dibond. As mentioned have never used it before so when I tried it out (a few posts back) that was all I had to try. Just thought i'd post that here.
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Re: Corafoam Adhesives testing

Post by Mark Summers »

Not sure what I'm looking at with the the piece of HDU a couple
posts above. I brought the picture into Photoshop to see what
I was looking at. Is the HDU finished out? Does not appear to be
porous. What I guess I'm getting at is Dibond with PU glue onto
HDU (painted or not) is probably not what you are looking for.
My guess is I would hand sand the Dibond and Liquid Nail the
pieces together.

If you are talking HDU to HDU Gorilla Glue (PU) is a good choice.
Signfoam had their own version once but no shelf life.
West System's epoxy will work fine when gap filling is needed.

Mark
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Re: Corafoam Adhesives testing

Post by Doug Bernhardt »

Hi Mark. That was a raw piece of Cora-foam and some dibond with PL premium construction adhesive. Did quite a few tests (not with the aluminum) and the epxoy's failed everytime. All the materials I did use are mentioned in the posts above.
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Re: Corafoam Adhesives testing

Post by joe cieslowski »

Just a bump to "stick" these three adheasive threads together. (at least for a while)

Joe
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Re: Corafoam Adhesives testing

Post by David Harding »

PL Premium is awesome adhesive but it is not rated for unfinished Aluminum. The Aluminum must at least be primed with an etching primer. It will turn loose from bare Aluminum in a couple years.
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