Thursday, January 29, 2015

DIY Bulletproof glass

I use this stuff around the shop for encapsulating various electronic boards.

While researching this, I found that there is another use for this stuff.  Turns out that craft people are using 2 part epoxy along with glass and chicken wire to make the old fashioned style of reinforced glass.

Basically you only need a few things to roll your own bulletproof glass. Or rather bullet resistant glass.  Nothing is ever bullet proof.

1 clear epoxy
2 glass, tempered glass preferred but it has to be special ordered
3 vacuum pump (like in a food saver with the food saver jar)
4 chicken wire (optional)

First thing you need to clean the glass thoroughly.  Do not use Windex.  Rubbing alcohol and a lint free rag or tissue is best.  Wear clean gloves.  Like those cheap ones with the rubber dots stuck to them.

You don't want fingerprints inside your windows do you?  

Windex has a surfactant and can potentially cause issues with adhesion so you don't want that.

Prepare your work space. This will get messy.  Newspapers are preferred underneath.

You need several small stands to put the glass on.  Some small blocks of 2x4 the same size will work.

Place first sheet of glass down on the blocks.  Do not put the blocks at the edges of the glass, place them a couple inches in from the edge.  You will see why when you apply the resin.

Mix your epoxy in a clean small bowl or jar.  My fiberglass girl uses those silicone rubber bowls for epoxy sold at dental supply places.

This bowl or jar needs to be small enough to fit in the food saver jar.  You don't want to ruin the food saver jar so you got a bowl inside it.

Next is to use the vacuum to remove the air bubbles from the liquid.  You will have to do several cycles to remove all the bubbles.

Pour the epoxy on the glass gently and avoid getting air bubbles 

Place second layer of glass or chicken wire and then glass.  Repeat as many times as you need to.

The epoxy will ooze out and some will run to the under side of the glass.

This is why you want the blocks not at the edge.  Once the epoxy starts to cure this will be trimed away with a sharp blade.

For experimentation, you can try using polycarbonate, acrylic sheet, and window tint in the sandwich.

You can even add in printing inside the sandwich like a sign or label.

This particular resin above has more elasticity than fiberglass resin btw.  Greater resistance against cracking.

While this is not quite the same stuff as the store bought brands (with the except of using the EVA film in the link above) It is much more economical for home use. 

One good use for it is in hurricane areas.

Some info I have come across says that the wire in the glass is supposed to increase fire resistance.

Another method and this is more of a translucent than clear glass is to fill glass building blocks like those wall blocks with clear fiberglass resin.  It is kind of expensive but it will let in light and will increase the strength dramatically.

If you try the EVA film I would be curious to see the results.  I can make the appropriate heaters to laminate the glass fairly easily.  The hardest part with the glass is not heating or cooling it too fast.  

I regularly heat ordinary glass to high temps with a fairly slow heat time with the printer bed.  I would be interested to try this...