Nick, in regards to the silicone skin not sticking to a vertical surface very well when you paint it into the mold, have you ever tried mixing cabosil powder in with the silicone for the first few painted layers?
I have never done this but am running into the same thing you are. It tends to pool at the bottom of the mold and ends up extremely thin near my seam-line.
If anyone has experience mixing cabosil with a soft plat-cat silicone, I'd love to hear about it.
Reply to discussion
Thanks Ron,
Using the powder on the tool might be the trick I was missing. And maybe using a razor, I've only used scissors. I was hoping there might be a way of wet sanding with a Dremel, but I'm not really surprised it doesn't work. Especially with this 00-30 stuff which is softer than shore-10. So it does sound very similar to seaming a foam latex puppet, except that the patching material is exactly the same as the rest of the body so it should move exactly the same.
Days of patching eh? No wonder the Cyclops looked so good!
I did paint a skin on first - 3 coats in fact. (It will all be there in timelapse at Youtube, when I've finished.) But silicone, even when it is thick, doesn't cling to a vertical surface much, it just keeps on flowing, so up near the seam line the skin was still fairly thin. The bubbles are just below the surface, and trimming off the flashing cut through to some of them. Filling them shouldn't be a problem. I didn't get any big air pockets - the armature is a pretty tight fit in places and I was afraid the silicone might have got trapped and left a forearm empty or something, but it got through.
The hands are not as good as my built-up hands - the wire barely fits in the thin fingers so I couldn't glue foam on, so the silicone doesn't have a grip on the finger wires. I should have wrapped fine thread on the fingers, anything to give it something to grip onto. But this body was meant to be able to wear any costume - including bare arms, shorts, bikini, or no costume - so it had to be all one piece. I've used the same trick as the Japanese jointed dolls, and made the neck part of the body, because I can hide the join under the chin better than down at the shoulder. I put a couple of photos up in the Silicone Valley photo album.
Using the powder on the tool might be the trick I was missing. And maybe using a razor, I've only used scissors. I was hoping there might be a way of wet sanding with a Dremel, but I'm not really surprised it doesn't work. Especially with this 00-30 stuff which is softer than shore-10. So it does sound very similar to seaming a foam latex puppet, except that the patching material is exactly the same as the rest of the body so it should move exactly the same.
Days of patching eh? No wonder the Cyclops looked so good!
I did paint a skin on first - 3 coats in fact. (It will all be there in timelapse at Youtube, when I've finished.) But silicone, even when it is thick, doesn't cling to a vertical surface much, it just keeps on flowing, so up near the seam line the skin was still fairly thin. The bubbles are just below the surface, and trimming off the flashing cut through to some of them. Filling them shouldn't be a problem. I didn't get any big air pockets - the armature is a pretty tight fit in places and I was afraid the silicone might have got trapped and left a forearm empty or something, but it got through.
The hands are not as good as my built-up hands - the wire barely fits in the thin fingers so I couldn't glue foam on, so the silicone doesn't have a grip on the finger wires. I should have wrapped fine thread on the fingers, anything to give it something to grip onto. But this body was meant to be able to wear any costume - including bare arms, shorts, bikini, or no costume - so it had to be all one piece. I've used the same trick as the Japanese jointed dolls, and made the neck part of the body, because I can hide the join under the chin better than down at the shoulder. I put a couple of photos up in the Silicone Valley photo album.
Friday, 26 November 2010 13:35
I'm betting the orange oil was the problem in the area you said was a bit poorly cured. The other two suspects you mentioned (kleen Klay and Naptha) are completely compatible with platinum silicone.
I've tried wet sanding seams on silicone (both manually and with a Dremel) and haven't had any luck with that. I think any sand paper strong enough to make a dent will make too much of a dent!
My process of patching the seams is really no different than what I would do on foam latex... I know I'm going to be adding material so, I start by cutting the smallest 'trench' I can to fill in with more silicone. I use a very fine pair of scissors and a razor for that part.
I fill the seam little by little and usually in two passes per area patched. The first step is filling where I just use a small sculpting tool to add the silicone into the 'trench'. When it gets just past the point where it becomes really thick (like pudding) I dab a soft paintbrush into some of that water soluble matting powder and blow on it to gently *puff* the powder onto the still very sticky surface of the patch. I keep adding powder until I can see no more shine.
At that point, if I need to sculpt any details into it to match the area around the patch, I dip my sculpting tool of choice into the powder so it has a fine covering of it - then use that tool to gently push whatever details I can into the silicone. Adding some 'Slo-Jo' silicone retarder into the silicone can make this soft stage of the cure last longer if you need more time to match details.
I will generally do a good length or maybe even the entire puppet with just filling the trench before starting the second layer of silicone patching. The second pass is almost like just adding paint to the surface over the patched area and feathering it out on either side of the patch. It's a VERY thin layer but, it really helps blend away a line that might still be visible. As you said about casting - nothing is ever 100% perfect so, making seams completely invisible is tedious and sometimes even impossible.
The puppets I'm making for this Sinbad film are obviously very important to me and I've put DAYS into patching seams to get them to the point where I thought they were good enough for camera.
I'm curious about your mold filling method? You said you got some bubbles on the shoulders and that makes me wonder if you put a skin into the mold first? Bubbles are something I'm happy to say I never have a problem with because my first step in casting is to always paint in a skin of a decent thickness into the mold - that's way I can be certain that even if the rubber contains air bubbles, they will be below the surface. After my puppets are cast, if I can feel an air pocket under the skin, it's no big deal to slice it open with a razor, fill it and forget it.
I've tried wet sanding seams on silicone (both manually and with a Dremel) and haven't had any luck with that. I think any sand paper strong enough to make a dent will make too much of a dent!
My process of patching the seams is really no different than what I would do on foam latex... I know I'm going to be adding material so, I start by cutting the smallest 'trench' I can to fill in with more silicone. I use a very fine pair of scissors and a razor for that part.
I fill the seam little by little and usually in two passes per area patched. The first step is filling where I just use a small sculpting tool to add the silicone into the 'trench'. When it gets just past the point where it becomes really thick (like pudding) I dab a soft paintbrush into some of that water soluble matting powder and blow on it to gently *puff* the powder onto the still very sticky surface of the patch. I keep adding powder until I can see no more shine.
At that point, if I need to sculpt any details into it to match the area around the patch, I dip my sculpting tool of choice into the powder so it has a fine covering of it - then use that tool to gently push whatever details I can into the silicone. Adding some 'Slo-Jo' silicone retarder into the silicone can make this soft stage of the cure last longer if you need more time to match details.
I will generally do a good length or maybe even the entire puppet with just filling the trench before starting the second layer of silicone patching. The second pass is almost like just adding paint to the surface over the patched area and feathering it out on either side of the patch. It's a VERY thin layer but, it really helps blend away a line that might still be visible. As you said about casting - nothing is ever 100% perfect so, making seams completely invisible is tedious and sometimes even impossible.
The puppets I'm making for this Sinbad film are obviously very important to me and I've put DAYS into patching seams to get them to the point where I thought they were good enough for camera.
I'm curious about your mold filling method? You said you got some bubbles on the shoulders and that makes me wonder if you put a skin into the mold first? Bubbles are something I'm happy to say I never have a problem with because my first step in casting is to always paint in a skin of a decent thickness into the mold - that's way I can be certain that even if the rubber contains air bubbles, they will be below the surface. After my puppets are cast, if I can feel an air pocket under the skin, it's no big deal to slice it open with a razor, fill it and forget it.
Friday, 26 November 2010 09:00
I just removed my very first silicone body cast from the fibreglass mould - not perfect but a usable cast. Much like foam latex - they are hardly ever totally perfect.
I poured in from the top, through the neck hole, so it would flow down the arms to the fingers. The fingers filled up ok but there are some bubbles at the top of the shoulders. Now that I look at the slightly raised mound of the shoulder, I should have seen that coming.
It came out of the mould ok with no release agent. However - on the puppet itself I got a good cure, but on the flange there is some uncured silicone. Good thing it's not the other way around! The only reasons I can think of are - Klean Klay for the dividing wall, but a sealed surface on the actual puppet. But I did test it on Klean Klay before and it was ok. Or, it might be that when I cleaned the mould I used some orange oil, then washed it away with naptha more thoroughly on the puppet mould itself than on the flanges. A trace of orange oil would be very likely to inhibit the silicone cure.
The Ecoflex 00-30 is soft and great for the main part of the body, but a bit like foam latex, it's actually a bit too soft for the fingers. Next time I'll use Platsil Gel-10 for the hands, and Ecoflex for the rest.
I've done a rough trim around the seam, but could do with some tips on finishing it for a completely seamless puppet. So far, some of the trimming leaves a slight raised ridge - any way to abrade this off? And in other places, there is a slight trough which will need to be filled with more silicone.
Ron - I know you produced a humanoid puppet with no trace of seams that I could see - and I know where to look. How you do dat?
As before, I've taken photos as I go. I'll see if I can post one in the photo section.
Next job is to make some heads, for this body and for my build-up bodies.
I poured in from the top, through the neck hole, so it would flow down the arms to the fingers. The fingers filled up ok but there are some bubbles at the top of the shoulders. Now that I look at the slightly raised mound of the shoulder, I should have seen that coming.
It came out of the mould ok with no release agent. However - on the puppet itself I got a good cure, but on the flange there is some uncured silicone. Good thing it's not the other way around! The only reasons I can think of are - Klean Klay for the dividing wall, but a sealed surface on the actual puppet. But I did test it on Klean Klay before and it was ok. Or, it might be that when I cleaned the mould I used some orange oil, then washed it away with naptha more thoroughly on the puppet mould itself than on the flanges. A trace of orange oil would be very likely to inhibit the silicone cure.
The Ecoflex 00-30 is soft and great for the main part of the body, but a bit like foam latex, it's actually a bit too soft for the fingers. Next time I'll use Platsil Gel-10 for the hands, and Ecoflex for the rest.
I've done a rough trim around the seam, but could do with some tips on finishing it for a completely seamless puppet. So far, some of the trimming leaves a slight raised ridge - any way to abrade this off? And in other places, there is a slight trough which will need to be filled with more silicone.
Ron - I know you produced a humanoid puppet with no trace of seams that I could see - and I know where to look. How you do dat?
As before, I've taken photos as I go. I'll see if I can post one in the photo section.
Next job is to make some heads, for this body and for my build-up bodies.
Friday, 26 November 2010 00:44
