Colour Measurement and Fastness - Chemical Processing - Textile Engineering & Fibre Science Previous Year Questions

The work of adhesion (Wₛₗ) depends on the surface tension (γₗᵥ) of the liquid and the contact angle (θ) formed on a surface and is expressed as γₗᵥ(1 + cos θ). The Wₛₗ for a given fabric and a liquid is reduced to 1/3ʳᵈ of the original value after oil repellent treatment. If the measured contact angle of the untreated fabric is 60°, the percent change in the contact angle after the treatment is __________.

If the reflectance of a dyed fabric at \(\lambda_{max}\) is 10 %, then the colour strength value (K/S) of the dyed fabric (correct up to 2 decimal places) is ______________.