ISO 24443:2021/DAM 1:2025(en)

AMENDMENT 1

ISO/TC 217/WG 7

Secretariat: INSO

Date: 2025-03-10

Cosmetics — Determination of sunscreen UVA photoprotection in vitro

Cosmétiques — Détermination in vitro de la photoprotection UVA

AMENDMENTS: Temperature, plate, mechanical spreading, sandblasted plate Rdq parameter, standard P8 specifications

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Foreword

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This document was prepared by Technical Committee ISO/TC 217 Cosmetics, in collaboration with the European Committee for Standardization (CEN) Technical Committee CEN/TC 392, Cosmetics, in accordance with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).

This second edition cancels and replaces the second edition (ISO 24443:2021), which has been technically revised.

The main changes compared to the previous edition are as follows:

— The temperature range has been clarified and revised,

— The plate use has been revised,

— The mechanical spreading has been clarified,

— The Rdq parameter of the sandblasted PMMA plate has been revised.

Any feedback or questions on this document should be directed to the user’s national standards body. A complete listing of these bodies can be found at www.iso.org/members.html.

Cosmetics — Determination of sunscreen UVA photoprotection in vitro

Page 5, section 5.6

Add the phrase “Product should be stored, in the dark, between 27 (±2 °C) and 32 (±2 °C) for at least twelve hours before the start of the test.”.

Add the phrase “The surface of sandblasted plates should be cleaned with a dry, antistatic microfibre cloth.”.

Add the phrase “The plates should be handled carefully by holding them by the edges, avoiding finger contact with the surface. A reference mark should be made on each plate to ensure the whole measurement process proceeds in the same order and direction each time. The plates shall be used without additional treatment on surface (chemical and/or physical). The plates shall be used only once.”

5.6 Substrate/plate

The substrate/plate is the material to which the test product is to be applied. For this method, PMMA plates with one rough side of the substrate shall be used and are commercially available. The size of the substrate should be chosen such that the application area is not less than 16 cm².

The specifications and preparation of this type of plate[17][18] are described in Annex D.

Product should be stored, in the dark, between 27 (±2 °C) and 32 (±2 °C) for at least twelve hours before the start of the test.

The surface of sandblasted plates should be cleaned with a dry, antistatic microfibre cloth.

The plates should be handled carefully by holding them by the edges, avoiding finger contact with the surface. A reference mark should be made on each plate to ensure the whole measurement process proceeds in the same order and direction each time. The plates shall be used without additional treatment on surface (chemical and/or physical). The plates shall be used only once.

Page 7, section 6.4

Add the phrase “Before application of the product, the temperature at the substrate surface should be between 27 (±2 °C) and 32 (±2 °C) and should be the same during the different steps of the process implying at least the weighting, product application, the spreading, the drying and the UV exposure steps.”.

Add the phrase “If a fingertip is used” in the paragraph 6.

Add the phrase “If an automated mechanical fingertip is used, a finger-cot (untextured and un-powdered latex) is first placed on the automated mechanical fingertip probe. It is important to verify that there are no creases in the finger cot after fitting and to verify that the finger cot remains firmly in place and does not break during the spreading procedure. If creases should appear on the finger-cot or if it breaks during the spreading procedure, it shall be replaced, and the plate currently being spread shall be discarded. To ensure saturation of the finger cot, a standard spreading procedure is first performed with a moulded PMMA plate, using the same protocol as described in 6.4. This plate shall be discarded and is not part of the final calculation. The same finger cot can be used for the complete set of plates of one product test, unless it gets damaged in the process, and shall be replaced between applications of different test products. Each time that there is a change in finger cot, the saturation procedure shall be repeated.”

Add the word “automated” in paragraph 10.

6.4 Sample application

Before application of the product, the temperature of the surface of the plate should be between 27 (±2 °C) and 32 (±2 °C) and should be the same during the different steps of the process implying at least the weighting, the product application, the spreading, the drying and the UV exposure steps.

The sunscreen product is applied to a new untreated roughened PMMA plate (with the roughened side uppermost) by mass, at an application rate of 1,3 mg/cm2 (±1,6 %) for moulded plates and 1,2 mg/cm2 (±1,5 %) for sandblasted plates.

To ensure dose accuracy and repeatability, the application area should be not less than 16 cm2.

The application dose may be determined by measuring the mass loss of the pipette before and after application of the product; alternatively, it may be applied based on volumetric measurements with consideration of the specific gravity of the test sample. Where possible, a positive-displacement automatic pipette should be used for this purpose.

Plates should be weighed after application phase for any non-volatile product.

The sunscreen is applied as at least twelve small droplets of approximate equal volume, distributed evenly over the whole surface of the plate.

If a fingertip is used, finger cots should not be used to spread the product on the plate. The fingertip used for spreading shall be dipped into the test product and then wiped to remove excess product before spreading the test product applied to the plate. The fingertip used to spread the product shall be cleaned between applications of different test products.

If an automated mechanical fingertip is used, a finger-cot (untextured and un-powdered latex) is first placed on the automated mechanical fingertip probe. It is important to verify that there are no creases in the finger cot after fitting and to verify that the finger cot remains firmly in place and does not break during the spreading procedure. If creases should appear on the finger-cot or if it breaks during the spreading procedure, it shall be replaced, and the plate currently being spread shall be discarded. To ensure saturation of the finger cot, a standard spreading procedure is first performed with a moulded PMMA plate, using the same protocol as described in 6.4. This plate shall be discarded and is not part of the final calculation. The same finger cot can be used for the complete set of plates of one product test, unless it gets damaged in the process, and shall be replaced between applications of different test products. Each time that there is a change in finger cot, the saturation procedure shall be repeated.

Deposit and weighing shall not take more than 30 s.

The first test plate applied should not be used for all the measurements, but to adjust the quantity.

After the sunscreen product is deposited on the surface of the plate, it shall be spread immediately over the whole surface using light strokes with human fingertip or automated mechanical fingertip.

Spreading should be completed in a two‑phase process:

First, the product should be spread on the whole area of the plate, using circular movements with a minimum of four passages from the top to the bottom of the plate. At the end of the first pass, a turn of the plate has to be done (¼ turn) to alternate passages, with minimal pressure and repeat this movement three times at least (about 30 s).

Then the sample should be rubbed on the plate surface using alternating horizontal and vertical strokes repeated at least three times alternate passages with a moderate but increased pressure. The second phase should last about 30 s with increased moderate pressure.

For alcoholic or oil products, application should be adapted as follows:

First, the product should be spread on the whole area of the plate, using circular movements with a minimum of three passages from the top to the bottom of the plate. At the end of the first pass, a turn of the plate has to be done (¼ turn) to alternate passages, with minimal pressure and repeat this movement two times at least (about 20 s to 25 s).

Then the sample should be rubbed on the plate surface using alternating horizontal and vertical strokes repeated at least two times alternate passages with a moderate but increased pressure. The second phase should last about 20 s with increased moderate pressure.

For all kinds of products, the treated sample shall be allowed to dry for 30 min to 60 min in the dark at the same temperature under UV exposure conditions (i.e. if UV source exposure conditions will be 30 °C (±2 °C), then the drying conditions should also be at 30 °C (±2 °C) ; or if the UV source exposure conditions will be 27 °C (±2 °C) , then the drying conditions should also be 27 °C (±2 °C)).

Spray products provided in a pressurized container shall first be degassed by puncturing a very small pinhole in the container to relieve all of the pressure, and then allowed to rest for at least 24 h at room temperature before accessing the liquid for testing.

Page 24, section D.2

Delete the value "11,004 ± 1,938" for the Rdq parameter of Sandblasted PMMA plate.

Add the value “12,0 ± 2,5” for the Rdq parameter of Sandblasted PMMA plate.

Sandblasted PMMA plate

Ra (μm) = 4,188 ± 0,514

Rv (μm) = 11,402 ± 2,499

Rdq (°) = 11,004 ± 1,938 12,0 ± 2,5

A1 (μm2/mm) = 238,252 ± 72,663

Ssc (1/μm) = 0,032 ± 0,015

Vvv (mm3/mm2) = 8,701,10-4 ± 2,325,10-4

Page 31, section E.3.2.2

Delete the value "7,0 ± 0,3" for the pH value.

Add the value "7,1 ± 0,3" for the pH value.

pH value (25 °C): 7,1 ± 0,3.

Page 31, section E.3.2.3

Delete the phrase "Viscosity: 16 000 mPas-1 to 19 000 mPas-1 using Brookfield DVIII Ultra, Spindle RV-5 at 10 r/min.".

Add the phrase "Viscosity: 12 000 mPa.s to 15 000 mPa.s using Brookfield® DVIII Ultra, Spindle RV-5 at 10 r.min-1.".

Viscosity: 12 000 mPa.s to 15 000 mPa.s using Brookfield® DVIII Ultra, Spindle RV-5 at 10 r.min-1.