Simple workshop checks for screening sheet material samples
Before paying for a laboratory test, crafters and small brands can screen material samples with simple workshop checks of their own. These checks are cheap and quick, and they are enough to drop samples that clearly do not fit. This note describes five of them, how to record them so the results can be compared, and their limits. One point must be clear from the start: a workshop check is a screen, not proof. Its results must not be used as the basis for a claim on a label.
Preparation
- Ask for more than one piece from the same sheet, at least palm-sized, and note the lot number or the date received.
- Cut each sample into several strips: some along the length, some across the width. Sheet materials often behave differently in the two directions.
- Prepare a record sheet, a ruler, a kitchen scale that reads in grams, a white cloth and a clock.
- Leave the samples in the same room for a day before testing, so temperature and humidity are equal.
Check 1: fold
Fold one strip twice at the same place, then open it. Look at the crease: is there a fine crack, a colour change or a lifted layer? Then fold and open the strip one hundred times, counting, and look again. Record the count and what you see. This is not a standard flex test. It only shows the samples that give up early.
Check 2: rub
Rub the surface with a dry white cloth, then with a damp white cloth, using the same pressure and the same number of strokes for every sample, for example fifty. Look at the cloth: has colour transferred? Look at the surface: is any part dull or flaking? Record it. Colour transfer to a white cloth matters if the product will touch clothing.
Check 3: wet
Weigh a dry piece, soak it in clean water for a fixed time, for example one hour, lift it out, pat it with a cloth and weigh it again. Calculate the gain in weight as a percentage. Measure length and width before and after drying. Note whether the material curls, stiffens or changes feel. For materials made from cellulose, this check is often the most telling.
Check 4: stitch
Sew two pieces with the thread and needle you will use in production, then pull the seam slowly until you feel it hold. Look at the needle holes: do they tear toward the edge? Then unpick the seam and look at the holes left behind. Record the needle and thread type. A material that tears too easily at the needle holes is hard to make into a bag or wallet.
Check 5: cut edge and smell
Cut an edge with scissors and with a cutter. Look at the edge: clean, jagged or fibrous? Does the surface layer separate from the base? Smell the sample when first opened and again after a day. A strong smell can be a problem in a workshop and in a finished product. Record what you find as it is.
How to record
For every sample and every check, write down the date, who did it, the lot number, the direction of the strip, the pressure or count used and the result in plain words. Take a photo after each check with a ruler beside the sample. With such records, two samples from two suppliers can be compared fairly.
Limits of simple workshop checks
- Simple workshop checks cannot replace standard tests. Laboratory figures come from set equipment and set methods.
- A result from one piece does not represent a lot, still less a whole production.
- Do not write “tested” on a label on the strength of these checks.
- If a sample passes every check, it only means it is worth testing further.
If your sample is a new material
For a new sheet material, including one from coconut, it matters even more to note the product stage of the sample before you read any check. The Kora coconut-derived material has published no test data and no product stage. Register your interest through the sample interest list if you want Kora to know which properties you need to measure. General guidance on choosing a material is on the choosing a material page.
Ask us
If you want to send us your workshop results or a list of properties that matter for your product, write through the contact page. We reply within two business days and say plainly what Kora can and cannot state yet.
Questions buyers ask
Which workshop checks can screen a sheet material sample?
Five: fold (fold twice, then fold and open a hundred times), rub (dry, then wet white cloth), wet (weigh before and after soaking for a fixed time), stitch (sew two pieces and pull) and cut edge with smell. Use the same pressure and count for every sample.
Can I write tested on a label after simple workshop checks?
No. Workshop checks are a filter, not evidence, and one piece does not represent a lot. They cannot replace standard tests with set equipment and methods. A sample that passes only shows it may deserve further testing.
How should I record workshop checks so samples compare fairly?
For each sample and check, note the date, who did it, the lot number, cutting direction, pressure or count used, and the result in plain words, then photograph it next to a ruler. Cut strips along both length and width, because direction can change behaviour.
What should I note first if my sample is a new material such as Kora's coconut-derived sheet?
Note the sample's product stage before reading any result. Kora has published neither test data nor a product stage for its coconut-derived sheet material. Register your interest through the sample interest list to tell Kora which properties you need to measure.