Printed hair foil ink vs bleach: how we test
We test printed hair foil against bleach: the foil is exposed to bleach paste, wiped, and checked for ink loss and for transfer to a white hair swatch. Developer strength, mixing ratio, contact time and temperature are recorded with each test, because a result holds only for the conditions it was run under.
Why this matters
A printed foil is folded around hair that is coated in lightener and left there for the whole processing time. A buyer of printed foil needs to know two things: that the ink stays on the foil, and that nothing from the ink reaches the hair.
Most printed foil is sold without an answer to either. This page sets out how we test it, including what the test does not prove.
Method
Printed ink vs bleach and developer
- What it checks
- Does printed ink come off or transfer to hair?
- How
- Expose printed foil to bleach paste under the conditions the product allows, wipe it, and check the print and a white hair swatch.
The steps, in order:
- Printed foil is cut from production stock, not from a specially prepared sample.
- Bleach powder is mixed with developer to a working paste, once with each developer strength tested.
- The paste is applied to the printed face, and a white hair swatch is wrapped in the foil against the print.
- The foil is left for the contact time.
- The paste is wiped off. The foil is photographed beside an untreated piece of the same print.
- The swatch is rinsed and inspected for any colour that is not its own.
What is recorded
Each test is recorded with the conditions it was run under. Without them a result cannot be repeated or compared, and “no ink came off” means nothing.
| Condition | Why it is recorded |
|---|---|
| Developer strength | Stronger developer is more aggressive on ink and coating |
| Mixing ratio | The ratio of powder to developer changes the strength of the paste |
| Contact time | Longer processing gives the paste longer to act on the print |
| Temperature | Heat speeds up the reaction, so a room-temperature result does not cover a heat processor |
| Bleach product | Formulations differ; a result holds for the product used |
Limits of this test
A test proves what it tested. It does not cover:
- Higher temperatures. Heat processors and climazones raise the temperature of the foil and can change the result.
- Longer times. Processing that runs longer than the contact time tested is outside the test.
- Every lightener. The paste is made with one bleach powder. Other formulations may behave differently.
- Other printers’ foil. A result applies to the inks and coatings on our foil.
If your customers use heat, or a lightener with an unusual chemistry, run the soak yourself on a sample before you approve a design. The steps above can be repeated at a colour station.
What this means for your printed range
Treat the bleach test as part of the specification of a printed foil, alongside the thickness and the size. Ask any supplier of printed foil for the conditions, the date and the photographs of their test, and for the result at the highest developer strength your customers use.
Print limits, plates and artwork are on custom printed hair foil, and the product itself on printed and coloured hair foil.
FAQ
Is printed hair foil safe to use with bleach?
Hair Foil Factory tests printed hair foil in bleach paste and then checks the print and a white hair swatch, recording the developer strength, mixing ratio, contact time and temperature. A result applies to our inks on our foil under the conditions tested; printed foil from another source needs its own test.
Does the ink transfer onto hair?
Ink transfer is checked with a white hair swatch wrapped in the printed hair foil during the test. After the soak the swatch is rinsed and inspected for any colour that is not its own.
Does heat change the result?
Heat speeds up chemical reactions, so a test at room temperature does not prove the result under a heat processor. The temperature is recorded with each test; if your customers use heat, ask for the test to be run at your processing temperature.
Are coloured foils tested the same way?
Yes. Solid-coloured hair foil is tested by the same method as printed hair foil: the same paste, the same contact time, the same wipe and the same white swatch. A coloured foil carries its coating over the whole surface, so the test area is the whole sheet.