Sunday, February 19, 2017

The best glues

Glue stuff I wish I had known earlier in life. Actually, only two of these existed when I was young.

Surface preparation for plastics, glass, and metal: roughen surface, soap and water, rubbing alcohol, eyeglass cloth. Nitric acid is used to prepare some metals for epoxy even after sanding (100 grit).

In general: epoxies and acrylic are best for glass and metal.  Silicone and polyurethanes can work on them, but these are best on plastics.

glass and metal:  3M VHB double-sided tapes, >40 mil thickenss ones.  5952 seems most popular.  To be ideal glass needs silane pretreatment and copper and brass need lacquer or varnish (they oxidize even after it's applied).  Needs 15 psi pressure.  50% strength bond in 20 minutes. Has 20 pound/inch peel adhesion.

Drying time: usually 18 hours is needed for epoxies, polyurethanes, and thick layers of super glue is needed to reach 1/2 of their final strength. 

Glass: If 3M tape can't be used:  Super glues are not so great.  Thinner is better, but a thick layer on top instead of in between parts can work. Epoxies for glass are best. The best is Aralite for glass.

Metal: Locktite Metal Concrete and Quick Steel are a lot better than JB weld and Gorilla glue. There are a lot of videos concluding this. Super glues and polyurethanes (goop, aquaseal) can work too. 

Plastics and rubber: Goop and Aquaseal. (polyurethanes)

Wood: wood glue and hot glue sticks for temporary holding while the wood clue dries.

Hot glue:  The newer, hotter, slow-drying glue sticks are pretty impressive, often doing a good-enough job on all of the above. Arrow SuperPower slow setting is one.

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