Methods and systems for quantitatively measuring photoprotection

1. A method of determining a quantitatively measured photoprotection of a photoprotective composition, the method comprising:

(a) distributing the photoprotective composition in a position in between a drawdown bar and at least one substrate positioned on a sample plate, to produce a distributed photoprotective composition;

(b) adjusting, with at least two spiral micrometers, a height of the drawdown bar relative to a top surface of the sample plate, wherein the height is from about 25 μm to about 200 μm;

(c) drawing down the drawdown bar across the sample plate to smear the distributed photoprotective composition, thereby forming a sample film having a thickness corresponding to the height of the drawdown bar relative to the top surface of the sample plate;

(d) drying the sample film to produce a dried sample film;

(e) measuring a UV absorption of the dried sample film to produce a UV absorption spectrum; and

(f) determining the quantitatively measured photoprotection of the photoprotective composition from the UV absorption spectrum.

2. The method of quantitatively measuring photoprotection of claim 1 , further comprising diluting the photoprotective composition with at least one solution to a viscosity from about 1000 cP to about 9000 cP before distributing the photoprotective composition in the position in between the drawdown bar and the at least one substrate.

3. The method of quantitatively measuring photoprotection of claim 2 , wherein the at least one solution comprises water, dimethicone vinyl crosspolymer, an alkyl acrylate dimethicone crosspolymer, a cyclopentasiloxane, or combinations thereof.

4. The method of quantitatively measuring photoprotection of a photoprotective composition according to claim 1 , wherein the thickness ranges from about 10 μm to about 100 μm.

5. The method of quantitatively measuring photoprotection of claim 1 , wherein drying the drawdown sample film comprises heating the drawdown sample at a temperature from about 25° C. to about 60° C. for a time from about 10 minutes to about 120 minutes.

6. The method of quantitatively measuring photoprotection of claim 1 , wherein the at least one substrate is selected from the group consisting of a glass, a polymer, a skin, a metal, and a textile.

7. The method of quantitatively measuring photoprotection of claim 6 , wherein the glass comprises silica, quartz, fused silica, borosilicate glass, soda-lime silicate glass, phosphate glass, or combinations thereof.

8. The method of quantitatively measuring photoprotection of claim 6 , wherein the skin comprises a porcine skin, a human skin, a cow skin, a mouse skin, a rat skin, a frog skin, a snake skin, or combinations thereof.

9. The method of quantitatively measuring photoprotection of claim 1 , wherein the substrate has a length from about 50 mm to about 100 mm, a width from about 10 mm to about 40 mm, and a height from about 0.5 mm to about 5 mm.

10. The method of quantitatively measuring photoprotection of claim 1 , wherein measuring the UV absorption of the dried sample film comprises measuring an absorbance at a range from about 200 nm to about 400 nm.

11. The method of quantitatively measuring photoprotection of claim 1 , wherein determining the quantitatively measured photoprotection of the photoprotective composition comprises integrating the UV absorption spectrum.

12. The method of quantitatively measuring photoprotection of claim 1 , wherein distributing the photoprotective composition in the position in between the drawdown bar and the at least one substrate comprises pumping, pipetting, syringing, pouring, positive displacing, scooping, smearing, spraying, squirting, transferring, displacing, or combinations thereof.

13. The method of quantitatively measuring photoprotection of claim 1 , wherein the photoprotective composition comprises a sunscreen.