Fig. 7From: The effect of traditional amur cork tree bark extract dyes on thermal stability of paper by accelerating ageingSEM photography for the surface of P (a, a1), P-A0 (b, b1), P-A1 (c, c1) and P-A2 (d, d1) before (a, b, c, d: 0 day) and dry-heat 80 days (a1, b1, c1, d1: 80 days)Back to article page