Check this out in the latest FWW (aug 07).They compared pva’s, epoxy, poly and hide glues. Surprising results, was glad to see one of my latest favorites (titebond 3) rate up there.
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Replies
SB,
I no longer subscribe to FWW, but would be interested in the results. Anyway you could post them?
Edit:
In my own experience, epoxies are the best as far as bonding strength, and also the priciest option, poly's #2, "white and yellow glues" are cheap in price, but often very cost effective if moisture is not going to be an issue.
WSJ
Edited 6/8/2007 10:15 am ET by WorkshopJon
Edited 6/8/2007 10:17 am ET by WorkshopJon
I saw that and was going to post here. Polyurethane was lowest on the list. I have never liked it, not have I had much luck with it, but thought it was me, as everyone else seems to rave about "Gorilla Glue". Nice to know that either PVA waterproof or just "carpenters" yellow glue are about the best.
"Nice to know that either PVA waterproof or just "carpenters" yellow glue are about the best"
Danno,
Well the FAA doesn't seem to agree, as the only adhesives they allow airplanes to be constructed with for the most part are epoxies.
Then again, I'm sure FWW testing standards are hirer than the FAA's
WSJ
Having worked with adhesives for making products in a different life, I think I can make some comments about adhesives.
First, and this is important for understanding any curing/hardening adhesive: The adhesive must wet the substrate before it cures. Once it hardens, it cannot increase its adhesion.
Now, once it has cured, what contributes to its durability? It is a combination of the flexibility of both the substrate and the adhesive. Consider bonding two pieces of thin sheet metal together, lapping them together with (say) a 1-inch bond.<!----><!----><!---->
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| : | |<!----><!---->
| : | |<!----><!---->
| : | |<!----><!---->
| : | |<!----><!---->
| : | |<!----><!---->
--------------------------<!----><!---->
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Now pull them apart <--><!----><!---->
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The metal will stretch most right at the start of the bond. This puts a very high stress on the adhesive. If the adhesive is brittle, it will delaminate from the metal, and you get a failure.<!----><!---->
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Now use thick metal. Here there is little movement right at the bond line, and the whole adhesive takes up the load. Result is a very strong joint.<!----><!---->
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So, the “best” adhesive really depends on what you are doing. When looking at the test results, look at how they tested things.<!----><!---->
Very true what JohnD said about what you're trying to glue, conditions...
The test covered 6 glues, type 1 PVA (titebond III waterproof), regular PVA (elmers), poly (Gorilla), epoxy, hot hide glue and liquid hide glue. This test was specifically for wood-to-wood bonds as it applies to furniture. This assumes indoors.
The ratings were:
titebond 3 (100% rating), close behind were epoxy (99%) and plain PVA (95%), liquid hide (79%) and regular hide (76%), last poly at 58%.
In our construction business, many applications are outdoors which rule out non-waterproof glues like PVA and hide.
Also, not all materials are freshly machined wood, PVA doesn't stick well to metals, plastics or finished/weathered wood. So that leaves only epoxies and poly for these applications.
Even in furniture refinishing which I do my share of, when rebuilding joints, it is sometimes impossible to clean the old glue from the joint. Can't use PVA in that case. That's where poly or epoxy comes in (non-historic piece).
Point is there is not one better glue type for all applications.