How this bench grades safety
Every card carries two independent labels. Difficulty describes how fiddly the procedure is. Safety describes what the procedure can do to you if it goes wrong. A card can be difficult and safe — building a supersaturated solution is fussy and harmless — or easy and hazardous, which is exactly what boiling sugar is.
Safety grades
| Grade | What it means | What you need |
|---|---|---|
| 1 · everyday | Food-grade materials, no heat above 60 °C, nothing that irritates skin or eyes. | A clean bench, a sink, and hands washed before and after. |
| 2 · goggles | Acid vapours, fine powders, alcohol, hot syrup below 100 °C, or a vacuum. | Safety glasses and an open window. Long hair tied back. |
| 3 · supervisor | Liquids above 100 °C, solution temperatures that can scald in under a second, or any electrical step. | An adult in the room for the entire run, oven gloves, and a clear route to the sink. |
Difficulty tiers
| Tier | Reading |
|---|---|
| 1 · Open bench | No special gear. Safe to run unsupervised by an adult nearby. |
| 2 · Steady hands | Some pouring and timing. Clear the bench first. |
| 3 · Long soak | Runs over hours or days, or needs a thermometer. |
| 4 · Hot work | Boiling sugar, concentrated solutions or open vapour. |
| 5 · Bench supervisor | Adult present for the whole run. Mains electricity is never used. |
Rules that apply to every card
- No mains electricity, ever. The one electrical card on this bench runs from a 9 volt battery. There is no version of any experiment here that justifies plugging anything into a wall socket.
- Never seal a reacting vessel. Pressure builds faster than most people expect, and glass fails before the lid does.
- Hot sugar is worse than hot water. It is above 100 °C, it sticks, and it keeps burning after it lands. If a batch of caramel scorches, take the pan outside and let it cool completely before you touch it.
- Nothing here is eaten unless the card says so. Several cards deliberately produce an inedible product, or leave raw egg sitting at room temperature.
- Never mix household ammonia with anything containing chlorine. That combination appears in one card only, and it is flagged there in bold.
- Ventilation is not optional. Alcohol, vinegar, ammonia and anything with a strong smell all need an open window, not a scented candle.
- Scale down, not up. Every quantity on this bench is written for one domestic run. Doubling a batch roughly doubles the heat released and the volume that can spill.
If something goes wrong
For a splash in the eye, rinse with cool running water for fifteen minutes with the eyelid held open, and keep rinsing on the way to medical help. For a burn, cool the area under running water for twenty minutes and do not apply ice, butter or cream. For a swallowed chemical, do not induce vomiting; take the container with you and call your local poisons service.
Questions about a specific card, or a correction to one, go to [email protected].