Hi
In reality there are really only 3 choices when it comes to the media used in etching glass and 1 of these is acid etching.
I wrote in my second post that as blasting generally goes by the name of sand blasting, sand isn't actually used in the blasting cabinet and this is for a few very good reasons.
1, it kills you
2, it kills you
3, well you get the idea.
Without the use of a very good breathing mask you will inhale the dust and contract
a very lethal lung disease called silicosis, so don't be tempted.
Of course there is another very good reason;
It is not very effective in what you are trying to achieve which is the removal of glass.
It is not very effective in what you are trying to achieve which is the removal of glass.
Basically to remove glass you require something harder than the glass, just like drilling a hole in mild steel, we don't use a mild steel drill to drill mild steel but an HSS drill. This is High Speed Steel which is a lot harder than the m/s so cuts through the softer material.
For glass etching the scale of hardness is measured in Mohs.
(Friedrich Mohs, (1773–1839), German mineralogist.)
This scale reads from 10 to 1 with diamonds being 10 down to talc at 1, mixed up in the middle is glass at between 6-7 and sand being between 6-7, coincidence; could it be that glass is made from sand.
What we need is something higher up the scale than glass and there are a few options available to us, I was at one point tempted by Garnet grit as it is a whole lot cheaper than the other options but has a hardness very similar to glass at between 7 - 7.5 so in reality it would do the job but very slowly. It would also breakdown a lot quicker and be useless after a few blasts.
The only option available to me when I first started to blast was and basically still is Aluminium Oxide, this is readily available from eBay suppliers in a variety of grits for around £28 plus £9 delivery for 25kg, it is also available from Machine Mart but in 20kg tubs for £36.
I used to buy it from Machine Mart about 8 or so years ago and it was a lot cheaper at around £18 a tub, it shot up in price overnight to near where it is now and I remember writing to the boss of Machine Mart complaining and asking if the Chinese had cornered the market. Can't remember what the reply was but more than likely it was bog off.
Anyway; Aluminium Oxide has a hardness of 9 and because of the availability is my preferred choice, it is available in a variety of grit sizes ranging from 60 to 220, the higher the number the finer the grit. I have been buying 180 but this will soon breakdown after use and become 190 then 200 etc so if you are starting out and doing a lot of practise maybe start at 150 medium and as you get to the stage of producing fine work for selling it will be down to 180 or maybe 220. It is also available in very fine white from the same eBay supplier linked here ASTBlaster there is also a lot of different size grits available for air eraser work.
Aluminium oxide is good but it does have a problem related to its use and that is static build up, I have never had a shock by this but it shows itself by the dust sticking to the glass you are working on and the glass you are looking through. A cloth is always handy to clean your glass but your glass screen will become etched in time with all the wiping, so have a spray cleaner handy to reduce the scratching risk.
I might run a ground line from the screen on my new cabinet, never know it might work.
The best but elusive media is Silicon Carbide, I would imagine it is available in the UK but I have never found it apart from in grinding paste form that I use for lapping valves or on emery cloth.
This is classed as the Rolls Royce of blasting media and has a hardness of 9-10 it cuts faster than Aluminium Oxide and breaks into sharper edges and last's longer. It also has a feature that I have never seen and that is it sparks (flashlight effect) as it cuts which gives you a type of laser aiming device so you know exactly where you are cutting on the glass, there is also no static associate with it's use. So you can see why it is the preferred media for the pro's and hobbyist alike (if you can find it) but as with everything you pay a premium for the best so it a lot more expensive.
I have linked some useful information in the knowledge section concerning the above so please study it as I will be asking questions.
Paul
(Friedrich Mohs, (1773–1839), German mineralogist.)
This scale reads from 10 to 1 with diamonds being 10 down to talc at 1, mixed up in the middle is glass at between 6-7 and sand being between 6-7, coincidence; could it be that glass is made from sand.
What we need is something higher up the scale than glass and there are a few options available to us, I was at one point tempted by Garnet grit as it is a whole lot cheaper than the other options but has a hardness very similar to glass at between 7 - 7.5 so in reality it would do the job but very slowly. It would also breakdown a lot quicker and be useless after a few blasts.
The only option available to me when I first started to blast was and basically still is Aluminium Oxide, this is readily available from eBay suppliers in a variety of grits for around £28 plus £9 delivery for 25kg, it is also available from Machine Mart but in 20kg tubs for £36.
I used to buy it from Machine Mart about 8 or so years ago and it was a lot cheaper at around £18 a tub, it shot up in price overnight to near where it is now and I remember writing to the boss of Machine Mart complaining and asking if the Chinese had cornered the market. Can't remember what the reply was but more than likely it was bog off.
Anyway; Aluminium Oxide has a hardness of 9 and because of the availability is my preferred choice, it is available in a variety of grit sizes ranging from 60 to 220, the higher the number the finer the grit. I have been buying 180 but this will soon breakdown after use and become 190 then 200 etc so if you are starting out and doing a lot of practise maybe start at 150 medium and as you get to the stage of producing fine work for selling it will be down to 180 or maybe 220. It is also available in very fine white from the same eBay supplier linked here ASTBlaster there is also a lot of different size grits available for air eraser work.
Aluminium oxide is good but it does have a problem related to its use and that is static build up, I have never had a shock by this but it shows itself by the dust sticking to the glass you are working on and the glass you are looking through. A cloth is always handy to clean your glass but your glass screen will become etched in time with all the wiping, so have a spray cleaner handy to reduce the scratching risk.
I might run a ground line from the screen on my new cabinet, never know it might work.
The best but elusive media is Silicon Carbide, I would imagine it is available in the UK but I have never found it apart from in grinding paste form that I use for lapping valves or on emery cloth.
This is classed as the Rolls Royce of blasting media and has a hardness of 9-10 it cuts faster than Aluminium Oxide and breaks into sharper edges and last's longer. It also has a feature that I have never seen and that is it sparks (flashlight effect) as it cuts which gives you a type of laser aiming device so you know exactly where you are cutting on the glass, there is also no static associate with it's use. So you can see why it is the preferred media for the pro's and hobbyist alike (if you can find it) but as with everything you pay a premium for the best so it a lot more expensive.
I have linked some useful information in the knowledge section concerning the above so please study it as I will be asking questions.
Paul
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