Etching Party Activity

At a recent children's party we etched metal. The resulting medallions/door signs came out well, so I though I would write it up.

The base material here is zinc plated steel, this is cheap and can be found precut into various shapes. I used ebay here.

Preperation

Test your material with different etch baths, I found hot vinegar worked well, adding salt helped. Also good was a standard FeCl3 bath, this is harder to get and to dispose of, but can be used cold. Neither of them etch much, but stain the surface a dark grey, leaving the untreated areas silver. Prepare a bath beforehand and keep it safe. Test different pens and possibly different etchants, because some combinations did not work, depending on the zinc surface and the pen the etch results varied. I aimed for etch times of 5 minutes, because this is comparatively easy to do, shorter is difficult to keep accurate and longer makes it difficult to distract the children for long enough. Some suggest adding citric acid, but I found that removed the pen. Hydrochloric acid is tempting, but is quite hazardous and makes really bad fumes; please avoid this.

On the day

Each child put on disposable gloves and a protective layer and then recieved a plate that had just been wiped with ethanol (sold here in Germany for lamps and cleaning)

They then drew their design with permanent markers (I used cheap copies of sharpies/Edding avaliable in ALDI). This is the reason for the protective clothing, otherwise there is a danger of marking stuff.

Then they carried out another activity while I etched the designs.

The pen was removed using the same wash ethanol (also good for removing mistakes, but this is difficult)

The Problems

Boiling vinegar really smells - only do this outside and don't breathe it in

Hydrogen is usually generated during etching, this should be done in the open so that it does not build up and flames kept away.

Other acids are worse than vinegar, except perhaps citric acid, which did not work for me.

More effective etching solutions become more dangerous, meaning that children in a party environment do not mix well. This means that carrying out the etching in a separate area away from the children is safest.

Disposing of the etchant can be difficult, you will need to check with local laws

Do not fill etchant into any food container that will be used for food ever again, it is not worth the risk.

The children played a long time with the used gloves and permanent markers, which kept them away from the etching, but was a danger of marking somebody's clothes.