Tests for Loctite Foam vs Great Stuff Foam
I have a crappy camera phone. Click on the pictures for a better view of tests and results.
I bought a can of Great Stuff Blue for Windows and a can of Loctite Multipurpose Spray Foam. I did not buy the Red can of Great Stuff. I believe the adhesiveness of both the red and the blue to be the same, but I like how the blue expands with less force.
Because of how much these cans cost, I came up with as many different tests that I could think of for these spray foams. Who knows what information some builder might need in the future.
While at Lowe's, I found that Dap also had a spray foam available, but since that wasn't in the original question, I didn't buy it. Also, it was expensive.
** While at Lowes, I could not find Loctite Window Spray Foam. Lowes dot com says that it is usually $7.67 but is on sale for $2.99. Figures
Test 1) Price from Lowes:
Great Stuff Red can. $3.78
Great Stuff Blue can. $4.48
Loctite foam Multipurpose. $7.98
Winner: Great Stuff
Test 2) Glue Test on EMT:
Since this experiment is for the idea of using EMT as a frame for a foamie, I took two pieces of 1 inch thick foam and Gorilla Glued them together.
After the glue dried, I cut six, 8 inch long by1 inch wide channels in the top piece of foam to simulate where the conduit would lay. I filled the three left channels with Great Stuff Blue and the three right channels with Loctite Multipurpose.
I used 2 foot long pieces of 1/2 inch EMT and placed them in the spray foam. I did not weigh them down because I wanted to see if the foam would push the EMT out of the channel.
Results:
1) Nether spray foam pushed the EMT out of the channel. Both wrapped around the EMT nicely.
2) The next day I tried the pull the EMT out of the channel. I started with the Loctite. On my first pull, I thought I was going to hurt myself trying to get it out of the channel. It didn't budge. I next went to the Great Stuff. I was able to get the EMT out of the channel on the first pull. It was difficult, but it did pull out of the channel.
I then tried to pull up the Loctite again. It took a total of 3 tries to pull the EMT out of the Loctite channel and it took one side of the channel with it. Remember, that side was glued down with Gorilla Glue.
Winner: Loctite
Test 3) Smearing Test:
When using Spray Foam as a glue, I like to spray it, then smear it with a piece of scrap wood or foam to get the bubbles out of it and use it just as a glue. This is why I like the Blue can over the Red. Once smeared, the Blue Great Stuff tends to rise less.
I tried the smear test on both the Loctite and the Great Stuff Blue here. I sprayed a little Great Stuff and Loctite them smeared them with a piece of scrap foam.
Results: The Great Stuff smeared and spread better then the Loctite. The Loctite was like smearing bubble gum where the Great Stuff was like smearing peanut butter. After they dried, the Loctite raised higher than the Great Stuff Blue.
Winner Great Stuff Blue.
Test 4) Smear Gluing Test.
I smeared some Great Stuff on a small foam block and placed another block on top of it. I did the same with the Loctite.
Results: I looked at how much the blocks separated from each other. They were both about the same. Then I tried to pull the block apart. The Loctite was only slightly harder to pull apart this time, but it was harder.
Winner Loctite.
Test 5) Re-usability Test:
The worst thing about Spray Foam is trying to use a can a second time. I tried to spray the can upside down, like spray paint, to see if it would quit spraying. Nope, I made a huge pile of foam on the wax paper I placed on the floor.
It reminded me of a cow patty.
****Legal Disclaimer** DO NOT TRY THIS AT HOME!
( THE NEXT THING I DID WAS STUPID AND EXTREMELY DANGEROUS AND I DO NOT RECOMMEND DOING THIS! I ONLY MENTION IT BECAUSE IT IS THE ONLY WAY I'VE FOUND THAT WORKS FOR ME.) ** 
While the foam was still wet, I took the straws off the cans and blew them out with an air compressor and I wiped off the ends. I then placed a wire inside the internal nozzle of the can.
There is a diaphragm inside the nozzle, if this is punctured, bad things, injuries, and a huge mess can happen. (THAT IS WHY I WOULD NEVER TELL ANYBODY TO DO THIS) I placed a piece of wire with a very blunt end inside the nozzle so that when the foam inside it dried, I could take out the wire and there would be a path for more foam to escape through. I DID NOT PUSH IT IN OR SHOVE IT IN. I PLACED IT IN VERY GENTLY!
NEVER TRY THIS WITH A CAN THAT HAS DRIED FOAM INSIDE IT! 
If you try this and something bad happens, don't blame me. I warned you.
Results: Both cans worked the next day. The Great Stuff worked better though. The Loctite didn't flow as well the next day.
Winner: Great Stuff.
Test 6) Expansion Glue Test:
On day two of the tests, I took the blocks that I glued together from the day before and glued the other side of them. This time I covered a block with spray foam and then placed the other block on top of it without smearing the foam first.
Result:
The next morning, they both expanded about the same amount. Then I tried to pull them apart. I started with the Loctite. I couldn't get it apart on the first try. I then tried the Great Stuff, I was able to pull it apart. I tried again with the Loctite. It took more force but I was able to break off half of the foam. The other half wouldn't budge.
Winner: Loctite
Test 6) Cut Test:
After the foam in the channels had dried, I cut off a layer of both of them.
Results:
The Loctite has smaller bubbles that were more uniform where the Great Stuff bubbles were inconsistent with each other and some were as big around as a pencil.
Winner: Loctite
Test 7) Paint-ability:
I put the EMT back into the channels and then cut off the excess foam. I then painted Glidden Gripper on both cut and uncut foam for both sprays.
Results:
On uncut foam, there were no reactions and the paint dried well. On cut foam, there were no reactions but the foam soaked in and did not dry in the 12 hours I let it sit. It was like painting with a foam brush and then touching the foam brush the next day. It will take a long time for that paint to dry.
Winner: None
My personal summary:
I'd say that Loctite Multipurpose was the winner, as far as being a better foam adhesive. It worked better for a framing adhesive with EMT and for that application, I'd buy it. However, for most other applications, Great Stuff or Gorilla Glue would be a better choice because of price and usability.
Remember, half the fun of building with foam is in the experiments.
Never argue with an idiot. They will bring you down to their level and beat you with experience.
by Postal_Dave » Tue Jul 30, 2019 4:00 pm 
