February 12, 2018

Glue for micromounting

If you intend to make permanent mounts, you will need to use glue. The old books recommend Duco cement, but nobody I know uses this anymore and I don't even know if it is still on the market. You will probably use at least two different sorts of glue. One to hold the specimen on a pedestal, and the other to mount the pedestal in the box.

Be aware that various trade names complicate and obscure what should be a simple issue. For example "Gorilla Glue" was once a name for a brown polyurethane glue (that you would be unlikely to use for micromounting). Now "Gorilla Glue" is a company that sells a variety of products with different characteristics, including a Cyanoacrylate "super glue". The same is true for Elmers, Loctite, Weldbond, and other products -- so pay attention.

PVA glue

As "white glue" this is the mainstay of micromounting. PVA is polyvinyl acetate. The old classic is "Elmer's" white glue. The original is non-toxic and water soluble.

I particularly like "Aleene's original Tacky Glue". This comes in a gold colored bottle and is sold in craft stores. It is thicker than regular white glue, which makes it very easy to work with. It can be removed by soaking in water,

I also use "Weldbond", which is another more runny white glue. I like this when I am joining two flat surfaces that mate nicely. Recent information indicates that this is not water soluble. I intend to make tests and perhaps abandon it if this is so.

One person I know got a gallon of the original Elmers, along with some lamp black and had it mixed at a paint store so he now has black glue, which is not a bad idea.

CA glue

Otherwise known as "super glue" and available from many vendors in various formulations. CA is cyanoacrylate.

This is perhaps the best way to attach a cork or wood pedestal to a polystyrene micro box. The glue partly dissolves the plastic making an extremely strong bond. Unless you use an absurd amount of glue, this would never be noticed though.

I am now using "Loctite Super Glue professional liquid" that I get in a 20 gram bottle at my local hardware store.

Another fellow I know recommends "Rhino Glue", which is only avaialable online (either from Amazon or Rhino).

RTV - i.e. silicone

This is sold as bathtub caulk or for other sealing uses. It releases acetic acid as it cures and smells like vinegar.

Not many people use this, and it is all but impossible to remove once it cures. You could of course view this as a virtue, but most people don't.

Polyurethane glue

This is what Gorilla glue is in most of its forms. Nobody that I know of uses the brown original Gorilla glue. Both a clear and a white variant are now available. The white stuff foams and expands to 3 or 4 times the original volume. It has been used with success on water soluble minerals that are otherwise problematic. It is easy to end up with a mess unless you use only a tiny amount. Some experimenting with scrap material is recommended before you try using it with valuable material.

The clear Gorilla glue variant does not expand, but also is said to not work as well with the water soluble minerals.

Other ideas

Some articles to read:
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Tom's Mineralogy Info / tom@mmto.org