Softening PMC-121/50 & PMC-744 Using ‘SO-FLEX’
Using ‘SO-FLEX’ By Weight . . . For best results, you should use an accurate scale to properly use ‘SO-FLEX’ with PMC-121/50 or PMC-744. ‘SO-FLEX’ should be weighed and must be thoroughly mixed (at least one minute) with the appropriate amount of Part B before combining with Part A.‘SO-FLEX’ is a softening agent that lowers the cured durometer of a variety of Smooth-On polyurethane products. The charts below indicate the effect ‘SO-FLEX’ has on full cured (7 days) PMC-121/50 and PMC-744 when added as a percentage of the total mix.
Parts By Weight
| Part "B" | + "SO-FLEX" (mix well) | + Part "A" | = Hardness* |
| 50 | 0 | 50 | 50 |
| 50 | 20 | 50 | 43 |
| 50 | 40 | 50 | 35 |
| 50 | 50 | 50 | 30 |
*Shore A hardness after 7 days.
Using SO-FLEX by volume with PMC-121/50 . . . if you want to add SO-FLEX by volume instead of by weight, you can do so by measuring out equal amounts of parts A, B or SO-FLEX. As indicated above, this will result in a cured Shore A hardness of 30.
Softening PMC-744 with ‘SO-FLEX’
Normally, PMC-744 cures to a hardness of Shore A 45. PMC-744 can be made softer and more flexible by adding different percentages of ‘SO-FLEX’ as indicated below.
Parts By Weight
| Part "B" | + "SO-FLEX" (mix well) | + Part "A" | = Hardness* |
| 50 | 0 | 100 | 45 |
| 50 | 20 | 100 | 40 |
| 50 | 40 | 100 | 35 |
| 50 | 50 | 100 | 30 |