Hydrospan 100 head enlarging tutorial by David Lee

"HydroSpan 100T works like a 3 dimensional copy machine enlarging any shape or design in perfect proportion and detail. You can increase the size of patterns, molds, art castings, foundry molds, fossil patterns or original art works without sculpting new masters." From Industrial Polymners Inc. website.

How many times have we as customizers seen a beautiful sculpt that was just way too small for a MEGO custom, everyday right? Well with Hydrospan 100 we can now make that head in MEGO scale. With a progressive expansion rate of 60%+ (each time after remolding), a 1/18 scale head (depending on size) will become a MEGO sized head in one progression with complete detail capture.

This resin is pretty amazing stuff, but it requires basic knowledge of head casting (see head casting tutorial before attempting). The basic concepts are the same, make a mold of the original. After the original (small head) is de-molded you are ready to get started. The resin itself is kinda thick like corn syrup, and after mixed is quite viscous. The two parts mix at a ratio of 2 parts A to 1 part B by volume, working life is 10-minutes, full cure time 24 hours. The hardness of cured HydroSpan is like really hard Gummi Bears. A trick to get a good mix ratio if you don't use graduated cups, is use three small Solo plastic cups, all marked at the same level. Pour two with Part A and one with part B and mix them all together. NOTE* judging volume is always tricky, and it's almost impossible to make just enough for one small head, so go ahead and make up several small head molds in a tray, and pour them all at the same time. If you are enlarging a MEGO head to 1/6th (Gi Joe) scale it's not a problem and you can use mold you already have.

After you have it all mixed together thoroughly you'll have about 10 minutes to pour it up. It will take that long as its thick! Push, shove and squeeze it into your mold, slamming the mold down to make it flow helps. You can smear it into the recesses details of your mold (Manufacturer says wear gloves, but I have never had any adverse side effects, it's gross but will wash off your hands and is non-toxic). If you use a pressure chamber for casting, all the better, although it's not needed. Now, you wait.. 24 hours is what they suggest, though I have de-molded earlier than that, just be patient. Once de-molded you will have a kinda brownish clear cast of your head, and this will be the first time you see where you have holes caused by bubbles hopefully you don't have any thing you can't just fill and resculpt easily. DO NOT try to fix anything at this point.

photo by Austin Hough

Now for the magic! Grab a container (Cool whip/Tupperware etc.) and fill it with water. Plop in your heads and walk away. NOTE* make sure you have enough room in your container for all your expanded heads to expand to there intended size. As the heads expand they will turn a very translucent green. I put them under the sink; the directions say to put them out of direct sunlight at 72 degrees. It says they will reach their full expansion in 10-14 days, but if they get to the desired size before that, you can pull them out immediately and mold them up. NOTE* the thinner details in the cast will expand faster at first (nose, ears, chin, eyebrows etc.) so your head will likely look cartoonish and weird until the other parts catch up (a day maybe). Once the part is at its intended size, simply pull it out and dry it off. Unless you have very thin protrusions it can be handled quite easily.

The last step is to mold it up. Make sure it's dry, and make a mold. I usually drive a skewer in it and suspend it upside down in a cup and pour the mold around it. NOTE* once a Hydrospan head is opened up i.e. a hole from the skewer, it can cause it to burst open if returned to water for keeping after molding. The water will enter the hole and start to expand it even more. Also if it's a tad big, just let it sit and check it as it returns to its original size; just catch it on the way back down.

Now that you have a mold of the newly resized head, you can cast it up and fill in any flaws or holes left from the original bubbles, then re-mold and recast. It's a slow process for sure but the results are worth it!