#2 Etch Test for Glass

This is a test for what I call Total Glass Dissolution.  Which is very simply put, the ability of the liquid in question to eat up and dissolve all molecular components of the glass.  That would be both the silicas and silicates.  In other words the calcium, sodium, oxygen, and silicon atoms.

To do this you will first need a small plastic cup.  About four inches.  Fill it half way with the liquid/product in question.  Then take a small/business card size piece of window glass.  I use the 3/16 inch glass from a glass shop.  You can ask them to cut you some two by three and a half inch (business card size) pieces.  They will even smooth the edges so you won't get cut.  Next just drop one gently into your plastic cup half filled with liquid.  The liquid should rise about half way up the glass plate. So that half is immersed and half is dry.  Let it set at room temperature for about a half hour.  Next remove and run it under the tap.  Then dry completely.  Inspect in bright light.

If total dissolution has occurred you will notice a rippled/orange peal like line where the liquid and air met.  You might see some clouding above this that won't go away.  The surface of the glass that was immersed should be very clear.  You might even be able to feel the rippled line with your fingernail.  Probably more on one side of the glass than the other.  And if you hold the glass closer to your face and look through it at the distant landscape, then move it a little, you should see the objects viewed through it move a little funny.  This line is the site of total dissolution.  Of course the surface that was totally immersed was also totally dissolved.  But the effect is much more noticeable at this line.  Again, if you want to do this test with something that is sure to cause this effect, pick up some sulfuric acid (battery acid) from the auto parts store.  But use caution.  Gloves and goggles are always best when working with acids.  It is a very strong acid.  About 37% clear sulfuric.

Written by Henry Grover Jr

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