Time Acids
Hydrochloric acid Sulfuric acid Phosphoric acid
0.1N 0.5N 1N 2N 0.1N 0.5N 1N 2N 0.1N 0.5N 1N 2N
2 days 48 48 48 49 48 48 48 49 48 48 49 49
7 days 49 50 51 52 49 51 52 52 50 52 53 55
15 days 54 55 56 57 53 56 57 58 56 58 61 64
30 days 56 58 62 63 56 59 62 69 60 64 70 74
 45 days 60 62 64 67 60 61 66 62 66 68 63 66
60 days 63 65 68 61 64 65 63 0 68 54 0 0
Table 1: Hardness (Shore-D) testing of polyvinyl acetate-Epoxy blend foam after soaking of different acids at different times.