Post by Lee on Dec 29, 2006 6:22:14 GMT 1
We have been talking about Hydroshrink in Joe Fay's bench thread and I thought it may be past time to start a thread of it's own.
First, here is the website of the company that makes Hydroshrink:
www.sculpt.com/catalog_98/CastingMaterials/HydroShrink.htm
In searching the web I ran into some other people that have tried the product. Here is one interesting website with modelers trying various ways to work with the material:
www.starshipmodeler.net/cgi-bin/phpBB2/viewtopic.php?p=497837&sid=829be6f86805c2298426bd58c43aa323
Here is a posting from that website about mix ratios:
"Some more experiments.
I haven't been pleased with the Hydroshrink (for many reasons) the two main ones are the softness of the fully cured material and the unpredictable warping of thin parts and edges.
I noticed that a couple of drops of unmixed Hydroshrink in my sink had set up after coming in contact with some water, so I decided to try an experiment to test the effects of various mixing ratios of Hydroshrink and water.
The ratios I picked were 1:1 (equal amounts of both) 1:2 (1 part Hydroshrink to 2 parts water) 1:4 (1 part Hydroshrink to 4 parts water - the recommended ratio) and 1:5 (1 part Hydroshrink to 5 parts water). Just to make the samples distinct, I used 5 ml of Hydroshrink for each test, and varied the amount of water. My "test piece" was simply the plastic mixing container for each sample.
I used cold water and mixed each sample. The radios didn't affect the gel times appreciably and after a few tens of seconds, I had four samples - 10ml (1:1) 15ml (1:2) 25ml (1:4) and 30ml (1:5).
The samples had set nicely, and the only difference was in their consistency. The 1:1 and 1:2 samples were firm while the 1:4 and 1:5 were very soft and Jello-like.
I placed the samples in my dehydrator for a couple of days, then let them fully air cure for about 5 days.
Here are the results
I haven't measured the exact shrinking ratios, but they're all roughly the same size, and roughly 50% smaller. The most noticable difference is that the 1:1 and 1:2 mix ratios did not deform - unlike the 1:4 and 1:5 mixes.
The 1:4 mix (which is the recommended ratio!) is badly deformed, and the 1:5 mix ratio is even worse. All four samples are rubbery but the 1:1 and 1:2 ratios are much stronger and firmer and would probably maintain their shape as RTV is poured over them. The 1:4 and 1:5 would probably deform under the weight of the RTV.
I think that the 1:1 and 1:2 mixing ratios produce the best results, with the 1:1 being the best. So much for following instructions!
Frank"
(Note: later in the thead Frank corrects himself about the shrinking of the various mixes)
and some talk about the air bubbles:
" tried using chilled distilled water, and it indeed reduces or eliminates bubbles. I'm not 100% certain, but I think I also got a slightly longer working time.
I made a hollow cast of the LE conning tower, and it came out with a perfectly smooth finish. I also added microballoons, thinking that it might make the material stiffer, but alas, it didn't.
So the problem of bubbles forming in the Hydroshrink is solved by using chilled distilled water (99 cents a gallon at the supermarket). The lack of stiffness in teh material is still a major problem, though. Even fully shrunk, the hollow conning tower is just too floppy to retain its shape.
Frank"
First, here is the website of the company that makes Hydroshrink:
www.sculpt.com/catalog_98/CastingMaterials/HydroShrink.htm
In searching the web I ran into some other people that have tried the product. Here is one interesting website with modelers trying various ways to work with the material:
www.starshipmodeler.net/cgi-bin/phpBB2/viewtopic.php?p=497837&sid=829be6f86805c2298426bd58c43aa323
Here is a posting from that website about mix ratios:
"Some more experiments.
I haven't been pleased with the Hydroshrink (for many reasons) the two main ones are the softness of the fully cured material and the unpredictable warping of thin parts and edges.
I noticed that a couple of drops of unmixed Hydroshrink in my sink had set up after coming in contact with some water, so I decided to try an experiment to test the effects of various mixing ratios of Hydroshrink and water.
The ratios I picked were 1:1 (equal amounts of both) 1:2 (1 part Hydroshrink to 2 parts water) 1:4 (1 part Hydroshrink to 4 parts water - the recommended ratio) and 1:5 (1 part Hydroshrink to 5 parts water). Just to make the samples distinct, I used 5 ml of Hydroshrink for each test, and varied the amount of water. My "test piece" was simply the plastic mixing container for each sample.
I used cold water and mixed each sample. The radios didn't affect the gel times appreciably and after a few tens of seconds, I had four samples - 10ml (1:1) 15ml (1:2) 25ml (1:4) and 30ml (1:5).
The samples had set nicely, and the only difference was in their consistency. The 1:1 and 1:2 samples were firm while the 1:4 and 1:5 were very soft and Jello-like.
I placed the samples in my dehydrator for a couple of days, then let them fully air cure for about 5 days.
Here are the results
I haven't measured the exact shrinking ratios, but they're all roughly the same size, and roughly 50% smaller. The most noticable difference is that the 1:1 and 1:2 mix ratios did not deform - unlike the 1:4 and 1:5 mixes.
The 1:4 mix (which is the recommended ratio!) is badly deformed, and the 1:5 mix ratio is even worse. All four samples are rubbery but the 1:1 and 1:2 ratios are much stronger and firmer and would probably maintain their shape as RTV is poured over them. The 1:4 and 1:5 would probably deform under the weight of the RTV.
I think that the 1:1 and 1:2 mixing ratios produce the best results, with the 1:1 being the best. So much for following instructions!
Frank"
(Note: later in the thead Frank corrects himself about the shrinking of the various mixes)
and some talk about the air bubbles:
" tried using chilled distilled water, and it indeed reduces or eliminates bubbles. I'm not 100% certain, but I think I also got a slightly longer working time.
I made a hollow cast of the LE conning tower, and it came out with a perfectly smooth finish. I also added microballoons, thinking that it might make the material stiffer, but alas, it didn't.
So the problem of bubbles forming in the Hydroshrink is solved by using chilled distilled water (99 cents a gallon at the supermarket). The lack of stiffness in teh material is still a major problem, though. Even fully shrunk, the hollow conning tower is just too floppy to retain its shape.
Frank"