Etching Cream Testing

Hi

We have talked about easy access into etching at home by using readily available etching cream, I say readily available which is not quite true for some as in a lot of the States in the USA it has become a little difficult to get hold off. 

Etching cream has a few dangers associated with it and because of this has been, if not totally banned, then has had it's over the counter easy accessibility removed. The dangers come from its chemical makeup and before using the cream a little time spent reading the MSDS (material safety data sheet) will make you aware of its dangers.

USA dept of health

Armour etch MSDS

Etchall

A little history of etched glass

A long long time ago, around 1850 actually, in a not quite quaint little island called Great Britain a giant monster called the Industrial Revolution was ravaging cities all across the land. People were coming from far and wide, leaving their wonderful country life of shooting the pheasants and beating the peasants to feed this ravaging monster, and the monster was getting bigger and bigger. 

The people were being massed together in tighter and tighter communities, made to work 25hr day's, living in slums with whole families in one small closet. Sanitation was basic if at all and slowly but surely the monster's ally disease took hold of the population. 

Many died and no one knew the cause until one day a brilliant young doctor realised that the drinking water was full of poop, of course this did not go down well with the population; being dead is not what they had come here for.

How can we survive with the water full of poop cried the populace, when a handsome young engineer came to the fore; build a sewer network to take away the stinky's said he; and the population of Great Britain rose up on mass and shouted NO! Let's drink more beer and thus the people had spoken. (and haven't stopped drinking beer since)
Beer bars sprang up on every corner of this idyllic isle (until the smoking ban and £3.50p a pint then they all closed)

Pretty much true really, for many the only access to clean water was beer which had been boiled during the brewing process, so was safe to drink, as more bars sprang up then the glass on the windows and the seating partitions began to be decorated by the artisans of the time and more and more elaborate work was done. Glass work in Britain had come of age.

Of course, Armour etch wasn't in the shop then so a more corrosive and much more dangerous acid was used.

Hydrofluoric acid was and still is used to chemically etch glass in a safe industrial environment however it is extremely harmful to humans and animals alike and should certainly not be considered for use at home, although it is still considered by some people wanting to etch glass.

This exert was taken from Everything Stained Glass and shows that ignorance of this highly dangerous acid is definitely still out there.

HSE

SO DON'T EVEN CONSIDER IT.

I have spent a little time researching etching cream and there are a lot of conflicting theory's out there on how to get the best results, in fact, a lot of people can't even decide on the spelling, Creme or Cream. Guess that depends where in the world you live.

I have considered everything I have read and here is my take on it, for what it's worth.

I have concluded that it ain't half bad.

It is very easy to use and gives an excellent finish. The finish is much more subtle than blasted glass, a lot less grainy textured, clearer and virtually disappears when washed. I would consider it ideal as a hobby for home with the added benefit of no major noisy equipment to be bought.

I've read a lot about splotchy finished, about shaking, about lumps and large grains, about temperature, about agitation of the cream, just about everything and watched a whole load of You Tube videos.

Well I have put it all together in a scientific experiment Ha!

I have bought 2 different types of cream for the test, the first being Armour etch which is widely available in most countries around the world and the second a virtually unknown from a large stained glass supplier called TGK in Germany which I bought from a UK outlet. The cream came in a plain squeezy bottle with no instructions or safety data as possibly decanted from a larger bottle. I have written to TGK asking for an MSDS but have been expertly ignored so after a search I believe I have found what they use which is called Glasotan etching cream

My experiment consisted of 3 main elements.

Time: The main concern's from what I've read are concerning the time the cream should be left on the glass, times range from 5 minutes to overnight, I am more inclined to believe it a matter of minutes rather than overnight so I gave a time of 15mins 30mins and 1 hour for both types of cream.

Agitation: The same problem of a splotchy finish keeps cropping up and after watching a video about the agitation of the cream to prevent splotchyness I incorporated movement into the experiment.

Manufacturers: Is one make better than the other.

I started by cutting the glass in 150mm squares and deciding on a pattern, my new cutting machine had arrived so after getting it set up I tested it on cutting the stencils.

I have rubbed the cuts of the stencil with white art pastel, I use these in preference to chalk as there are very soft and don't lift the resist, the cuts are now highlighted for easier weeding.

I weeded all of the patterns.

I next set out all of the required items, apart from the roller which has gone walkabout.

After washing the glass in a vinegar solution, I dried and cleaned with the alcohol wipes and stuck on the stencils.

A bit of interesting reading that came to light was that the best temperature to activate the chemicals was 60 degree C, so after a vigorous shaking of the bottles I let them sit in hot water for 10 mins to soak up the heat, I kept renewing the water to maintain the temp.

I was then ready, so another vigorous shaking of the bottle and I started with the Armour etch on a 15 minute test piece.

I had to decide the best way to achieve the agitation part of my experiment and decided on a battery toothbrush (sorry Lynne but a sacrifice required) I used this to apply the etch and kept it running to get it into all of the pattern. The thickness as you can see is nicely covered but not overly thick and I gave it another rubbing with the toothbrush vibrating every 5 mins for the 15 min test and every 15 mins for the others.

I set up a timer and got to work on the next test.

The etch cream is re-usable which is a good thing as it is not cheap, the Armour cost around £15 for the 10-ounce bottle from Amazon and the TGK was £8.50 for 60ml (approx 2 ounces) on eBay. The Armour is definitely the best value.

I used the plastic end of my smoothing tool to remove the cream when the time was up and replaced in the bottle, this was the 30 min test.

I then washed the glass getting all of the cream out of the pattern.

I repeated the test until all of the pieces were finished.

After the removal of the resist, I gave them a good clean again in a vinegar solution then alcohol wipes before comparing, first the difference in cream manufacturers.

The first is the 15 min test and they both look good, missed a little resist on the TG which didn't get etched but apart from that Ok.

The 30 min test came out just as good no splotchyness at all.

The 1 hr test is fine as well.

Conclusions

Time
Another thing I read from someone is that once the etching process has been complete it basically stops, it does not get anymore etched / whiter so to speak and examining the 15 min to the 1 hour I think I agree. I should have done a 5-minute test to see the difference between the 5 and 15 but leaving it on for an hour or even half an hour does not seem to matter.

Spotchyness
This problem has not occurred, the look of the etch is equal over the complete work, this may be down to my agitation of the cream or the 60-degree temp I don't know.

Depth of etch
Having said that the time does not matter on the whitening of the etch it does on a fingernail scratch test over the work, it feels slightly deeper, maybe only microns but if using a colouring such as Rub & Buff then the small increase in depth may be the difference you require.

Well not really scientific as I could have added a few other parameters but what the hell I'd ran out of glass.
I can see no difference between the two makes so go with what you have available to you and it should come out as good as any other make.

Paul