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Old Jul 26, 2006, 04:46 AM
n-tropic is offline
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Discussion

All PU glues are equal but some are more equal than others?


I've heard it said that some PU glues are superior to others for the purposes of bonding EPP and I wondered if anybody out there had any concrete experience or information about this.

I have always used Gorilla Glue and have been very happy with it but I was running out recently and found some much cheaper stuff by Geocell (9.07 for 500ml) at a builder's merchants. This claims to reach handling strength in 5 minutes and reach full strength after 24 hours. Initial mucking about reveals the 5 minute claim to be rubbish. Interestingly the Geocell glue specifically says "not suitable for polypropolene" but presumably this relates to solid PP which will be shiny, rather than Expanded PP which has a cellular structure which allows penetration..

Generally I tend to think glues which take longer to set make stronger bonds. If a PU glue foams quicker I wonder if this will aid or inhibit penetration into the foam.

Anyway, blah, blah, blah. If anyone has any useful info on their preferred PU glues I would be most interested. Obviously availability in the UK is important for me. I've not seen that Elmer's stuff in the UK which I've heard of from US posts.

Below is a little unscientific test I'm running. I'll post my findings after it's all had 24hrs to go off.
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Old Jul 26, 2006, 04:43 PM
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n-tropic, yes they do vary, I have used 3 types, the Geocel is the worst at drying (no way even after 4 hours! ), the ELCH stuff also available at Screwfix is bit better but not as good as the Elephant PU they use to sell which would dry off rock hard (when fresh) in about 20-25 minutes. If you see it anywhere please let me know.

I might try the Gorilla stuff next to see if it can match the old Elephant PU (which also gave of the strongest fumes that would burn your eyes , use outdoors only)

Using fast PU spoils you as you can finish a big wing spar job in one morning,

BTW Geocel is not much of a benchmark to test other PU's against, I would be interested in knowing how hard they both are after 3-4 hours in your side by side test.

Tony.
Old Jul 26, 2006, 04:59 PM
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Dont know if the have Selley's products in the UK but the aquadhere with PU technology which is available here in Oz is excellent $20 Aus for 750 mls from Bunnings Hardware 1 bottle has lasted me 12 months I'm due to get a new bottle now but Ive used it on everything.
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Old Jul 26, 2006, 05:12 PM
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Thanks Steve, I'll have look for it, how long does it take to go hard? Tony.
Old Jul 26, 2006, 05:38 PM
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Im using the Elmers brand Ultimate Glue. How does it compare to others?
Old Jul 26, 2006, 06:07 PM
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Quote:
Originally Posted by Taylor Mullin
Im using the Elmers brand Ultimate Glue. How does it compare to others?
Never tried it.
Old Jul 26, 2006, 06:12 PM
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Tony,
Ive found it starts to foam after about 15 minutes and is hard after around an hour and a half in the sun I green trim it after around 40 minutes to save alot of sanding
I've used it in my Jart as well under the wing to fuse join I swear by it.
SteveW
Old Jul 26, 2006, 06:14 PM
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I have seen emlers here in Oz but have not tried it either must do a comparision for not only cure but cost factor as well..
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Old Jul 26, 2006, 06:21 PM
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Steve, Selley's seems to be an Oz brand, just noticed Titebond PU is available in the UK. Still searching for the first type I used. Tony.
Old Jul 26, 2006, 06:33 PM
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I wonder if we could export you a bottle
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Old Jul 26, 2006, 08:24 PM
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Quote:
Originally Posted by Antonsoarer
BTW Geocel is not much of a benchmark to test other PU's against, I would be interested in knowing how hard they both are after 3-4 hours in your side by side test.

Tony.
Ahh now, the truth is I did a similar test with the Geocell the day before but pulled the pieces apart after 8 hours. The glue had not set properly at all and was still sticky. It also hadn't penetrated the foam particularly well. This spured me to try the comparison to see if the Gorilla really was better.

The Geocell seems to start foaming pretty quickly but obviously this is no indicator of how quickly it sets.

Steve
Old Jul 26, 2006, 08:47 PM
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I've used both Gorilla glue and Elmer's ProBond Polyurethane glue before with excellent results and can't really report any differences in the two. For all practical purposes, they're identical.

Now Elmer's has come out with a new Polyurethane glue which they call Elmer's Ultimate. They claim that it's 40% stronger than Gorilla Glue. I haven't tried Elmer's Ultimate yet but I suppose I will eventually.

However I'm not too excited 'cause Gorilla and ProBond Polyurethane exceed my needs by a substantial margin. That, and I know how they react and how to work with them so there won't be any surprises.

Pete
Old Jul 26, 2006, 08:47 PM
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I've also used the Elmer's version with good success, it seems pretty much identical to the Gorilla brand. Like one of the other posters, I 'green trim' it after it sets up but before it hardens to save a lot of sanding.

be careful as the foaming action can result in this stuff getting a lot of places you may not want it. i mask the heck out of the surrounding areas with wax paper and masking tape, and checking back for a 'green trim' before it hardens is essential if you want to be able to remove the overflow easily.

i smear some of the mix on a scrap and keep it handy so I don't need to disturb the glued area to check on it's curing process. As soon as it is set up up to where it is still a bit squishy but it rebounds and you are not breaking the tiny foam bubbles when you poke at it, it's ready for a trim and has a great consistency for getting a good trim cut.

Typically at room temperature this occurs 1-1.5 hours or so after application, wait too long and it gets hard real fast, then you have a lot of extra sanding ahead .
Old Jul 27, 2006, 12:33 PM
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I couldn't say these results are conclusive.

Subjectively the Gorilla Glue sample seemed a bit harder to pull apart (you'll see I tore the foam in the process) even though the Geocell looked like it might have penetrated the foam a little better. Like I say it's all a bit subjective.

In fact I am surprised that neither glue penetrated very far. When you do a spar the stuff always migrates to the lower surface of the wing where baking parchment stops it from bonding the wing to the bed. I guess there's no benefit in being shy with the glue bottle as you want the stuff to wick well in to the foam.

Steve

PS I've adjusted the pics a bit as the flash burnt them out somewhat.
Old Jul 27, 2006, 02:10 PM
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Do you get Brummer's in Oz?
They have 2 PU glues, the normal (which takes about 4 hrs to set) and the "Fast drying" which sets (and foams more) in about 20 mins.


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