Hydrospan 400 Shrinking Resin
The HydroSpan 400 product was invented by Industrial Polymers for reducing the size of 3 dimensional objects while maintaining high surface detail. The HydroSpan 400 product is a urethane resin which quickly cures when mixed with ordinary tap water. We recommend using cold water (ice cold water) to extend the very short working life of this product. To use, create a mold of the original object you which to shrink in size and then fill the mold with HydroSpan 400. The HydroSpan 400 will rapidly cure in your mold within minutes. Remove the HydroSpan 400 casting from your mold and place in a low humidity environment to begin the reduction process. You have only 1 to 2 minutes to pour this material into your mold after mixing with cold water before it cures. See video demonstration on this page. The amount of water used in the reaction depends on the amount of reduction you wish to achieve. See HydroSpan 400 technical data information PDF file on this page or quick reference chart bottom of this page.
The HydroSpan 400 shrinks proportionally as water evaporates out of the cured product. You may use a food dehydrator to speed the shrinkage process or simply leave the casting in a low humidity environment for it to shrink; it produces very accurate reductions of any casting. Most of our experience with this product has been with shrinking objects with a starting size of approximately 15cm in diameter. Very large castings may be more difficult to shrink because it will take much longer for the water to evaporate from the HydroSpan 400 casting. You should monitor the shrinking process until the desired size is achieved. When the desired reduction size has been achieved you will make your new production mold from the reduced HydroSpan 400 casting. You may use molds made from urethane rubber, silicone rubber, metal or plastic to cast HydroSpan 400. Silicone spray mold release or wax based release agent must be used to prevent sticking of HydroSpan in your mold, except for silicone rubber molds which are naturally releasing.
One customer reported that he was able to shrink a larger casting by segmenting the casting into smaller pieces with a sharp knife, shrinking the pieces to the desired size, then gluing them back together. A new mold was then made from the reassembled reduction. See Technical Information and Material Safety Information on this page for more complete instructions. (We also sell an enlarging product – HydroSpan 100)
Quick reference chart for determining how much water should be added with resin to achieve correct reduction size
|HydroSpan 400 resin / water solution||Gel Time||Size of finished part Compared to Master (100%)|
|Less than 1 part water to 1 part resin is not recommended|
|1 Part Resin/ 1 Part Water||1 min 0 sec||59% of original size|
|1 Part / 2 Parts||1 min 10 sec||45%|
|1 Part / 3 Parts||1 min 15 sec||36%|
|1 Part / 4 Parts||1 min 15 sec||30%|
|1 Part / 5 Parts||1 min 15 sec||27%|
|1 Part / 6 Parts||1 min 20 sec||23%|
|1 Part / 7 Parts||1 min 19 sec||21%|
|1 Part Water/ 8 Parts Water||1 min 30 sec||19% of original size|
|Greater than 8 parts water is not recommended|