This is fascinating stuff. How many times will the finished mold be good for?

I'd hope 40 or 50 casts at least. I wouldn't make a mould this way if I intended vibrating it - in that case I'd make a urethane skin and fibre-glass casing. I'll be using this mould myself, and I'll be going pretty easy on it. The first thing I'll do, before casting in hypertufa, is take a plaster cast, and store that away in case the mould ever has an accident.

It's turned out a bit of a monster - the photos don't give a good idea of how big it is :o( Here's a photo with a rubber glove draped over the forehead for scale.

I'll definitely be casting it hollow!

Thinking about how to make it hollow, one thing that I'm going to try is filling lots of small bags (size of small bags for freezing leftovers) with very tightly-packed peatmoss. Build up a skin on the inside of the mould, pack in lots of the small bags of peatmoss, build up the back of the object over the bags of peatmoss. When the 'tufa has set, pull out the bags one at a time. I've tried doing it with one large bag of peatmoss, but it's not very convenient - it's difficult to get it into the right shape, difficult to pack the peatmoss solidly enough, and you have to cut the bag and empty it out after each casting, which is very messy.

He's gorgeous! Can't wait to see the first casting.

Would it have been possible/advisable to use pieces of fiberglass glued on with resin/epoxy in place of the scrim and plaster?

I really don't know what I'm talking about. But won't the plaster that holds the scrim in place eventually crack and fall off? Or will there be a mother mold as well?

All in all, a truly informative tutorial for the large stuff. Makes me want to drag out the sketch book and get started. :-)

Rockyn - I'd make a fibreglass (i.e. resin and fibreglass) casing for a mould that was going on a vibrating table, because it takes a lot of punishment. This mould will be used much more gently - and I'll be reinforcing the outside with expanding foam, which is very tough.

I won't store this mould outside, it will be stored/used in a shed.

Running Dog, your sculpture is absolutely wonderful. The tutorial is extremely helpful. Thanks so much for taking the time to make the tutorial.

I was wondering about the French Polish. In the picture with the French polish, I noticed that there were crease or crack lines. Will those show up in your silicone mold? Also, would a majority of the clay reuseable after you pull the mold away (except maybe the small bit attached to the polish)? Just wondering.

Again, thanks for the tutorial.

Serene

Hi SereneSeen - the cracks were caused because the clay was drying out from the inside - I made the piece by putting a very thin layer of clay on top of polystyrene that had been taped together, with one layer of plastered scrim on top of the polystyrene. So it wasn't quite airtight underneath, and was able to dry out a bit from underneath, overnight. I packed a bit of clay into the crack just before applying the silicone, a crack like that would be visible in the mould.

I re-use clay like that - it will be a bit lumpy, but that doesn't matter when you're building up something large. You can use the rough lumpy clay to build up the main shape, use good clay for the visible layer.

Rodkyn - thought you might get a giggle from the fibre-glass mould in the attached link. Now this one's BIG! It's 14'6" long by 9' wide. It will be cast in the spring by my local council, it's going into a large park in Dublin. It will be cast in white cement and crushed granite. I asked the mould-maker to get up there to give a sense of scale to the photo. When a mould gets this big I bring in the professionals! :o) If you're wondering about how much a mould this size costs, it was roughly 4,000, including materials.

The silicone-in-soapy-water idea worked great. I had no idea that sticky stuff could be controlled by a little soap and warm water.
Not knowing what I was doing (I have never done any of this before) I grabbed up a little iron bird statue and smeared some vaseline on it and buried it half down in wet clay so just one side of the bird showed. Then I smeared the silicone on the exposed metal and onto the clay to make an "edge" around the bird mold. After an hour or so the silicone felt "set" so I erected a little cardboard fence around it and poured plaster of paris in so the mold would have a srong support of plaster under it. An hour later I inverted the whole project and peeled away the wet clay I had embedded the bird in. Then I tried to carefully pry up the iron bird, leaving the silicone layer in its plaster support. welll...... that was a big failure. The silicone tore in places. What did I do wrong?
I am guessing I should have let the silicone set up for longer than a couple of hours. Since this was such a small test I was pretty lavish with the silicone and probably glopped it on about half an inch thick. How long should it take for a half inch thick layer of silicone to set?

thanks!
Laura

Laura, thick silicone will take weeks to set. Silicone sets only when it is in contact with air (actually it is the water in the air that cures it). A thick layer sets at the surface into an air-tight skin and the inside stays liquid for ages. Use thin layers and don't apply the POP too soon.

Running Dog-

I love your sculpture! He is very impressive. Thank you so much for sharing your creative process in such detail. I am inspired!

Off to the garage to look for caulk-

Jo

Sorry - as shrubs_n_bulbs says, don't apply the plaster too soon. Forgot to mention that you need to allow the silicone to cure for AT LEAST 24 hours before applying the plaster. The longer you leave it the better. I put smaller moulds outside to cure, because the smell is pretty overpowering indoors.

Loved the King of the castle! Is it an Easter Island man also?

LOL, my daughter thought it was a submarine! Doh!

No, it's a head partially submerged in the earth. It forms the centre of a labyrinth.

I've made an album, and put in pics of the clay head just before the mould was made, and the model of how the whole thing will look in the landscape. It gives some idea of how the finished work will look (hopefully!).

If you're interested in what software I used for the computer model, google Bryce. It's a really nice 3d modelling program, very easy to use, and not too expensive.

Hope that you can access the whole album with the attached link.

PS - when you've accessed the album, click on the 'Slideshow' button, it makes the album a bit easier to view.

Cast into the mould about a fortnight ago, intended to take it out after a day or so and clean it up a bit. But with Christmas stuff going on I forgot about it until yesterday.

Don't think I'll be making too many of these :o( Had to have help maneouvering the mould over to release the cast, and carrying it into the garden to be photographed. It's very heavy even though it's only about an inch thick, and a 1:2:3 mix (cement, sand, fine vermiculite). I def'ny wouldn't be able to shift these around by myself.

{{gwi:74946}}

It's bigger than it appears in the photograph!

It looks very dark for a 1:2:3 mix? Mine come out the same colour as regular concrete. Did you use a dye?

Nope. Grey cement, grey sand, and the fine horticultural vermiculite. The cast is still wet, though. The red streaks are remains of the clay that I used to make the original, I didn't do a very good job of washing out the mould before casting.

WOW Very nice to bad it isn't easy to produce more. It looks nice with the red streaks in it. Maybe a red wash of some kind.
Paws

FANTASTIC! Thanks for the great tutorial, too.

I've kinda gone off the thought of Easter Island heads, anyway, since remembering the environmental catastrophe that they led to on Easter Island :o(

Are you thinking maybe the entire industrial and agricultural output of Ireland might get diverted into massive hypertufa statues?

Exactly ;o)

Running Dog,

Great show on the tutorial. Could you show us the back and how you created it? This is inspiring me to create something.

Jerry

Jerry - the back is very plain. I put a one-inch or so layer of hypertufa into the mould, then I laid sheets of polystyrene into the cavity, enough to bring the level up (hope that's clear) and put another one-inch layer (of hy[ertufa) on top of the polystyrene. So the back is just dead flat, and the centre is filled with polystyrene insulation sheeting.

Thank you for sharing your process. I have a couple of questions. Are you using 100 percent silicone caulk and can burlap be used for the shree?
I have used silicone caulk to make a mucho smaller mould than this one of yours.It's amazing to me that warm water and soap can make the silicone so much easier to work with than what I was going through. Thanks so much for this method!

Dear Mr. Dog,

All your hard work paid off, he looks superb!

Loved the labyrinth pics. The face looks somewhat effeminate, IMO, and very mysterious. Like a cover for a fantasy novel. Is the face to be concrete? And the labyrinth is actual shrubs, I suppose?

LOL, went back over the (now bookmarked) tutorial and can only imagine what would happen in my house iffen I used the dining table for such a project. My other half would never let me hear the end of it.

Now, off to finally start a backyard dragon design -hopefully in time for the start of swimming pool season....hope he looks half as good as yours.

Hmmnnnn...I posted a reply to Sarah, but it's disappeared into the ether :o:

Hessian is the same as burlap, as far as I can make out. Both are coarse-weave fabrics that are used for things like sacks, aren't they? Any coarse, strong fabric will strengthen plaster of paris, and allow you to make a lighter case-mould.

I buy the silicone by the box from a place that supplies double-glazing firms. Worth doing if you use a lot of it. As you said, it needs to be 100% silicone, the clear variety.

Rockyn - Mrs. Dog to you ;o)
The labyrinth walls will be made of earth. Later this year it's going into a large park which is being re-organised, they'll have lots of earth to spare from work elsewhere in the park. Below is a link to the park.

Thank you so much, Ms Dawg, for sharing this. I am very excited about it. I have experimented with silicone with varied success. Your method will take care of most of the problems I encountered.

running_dog,

Hi,

first, thanks for taking the time to, generously, pass on the techniques that you're using. Very nice tutorial.

Something that I'm wondering about; you mention taking a plaster cast of the completed mould as a backup. When taking such a step would you be able to make the cast with a layer of plaster, or would this require the mould to be filled?

thanks,

Sean

Searched for this link to give to someone, and laughed when I saw the photo above. Y'know, I STILL hate it. In fact, I dislike it more and more every day. I've made just the one, could never be bothered making another. I've started casting my smaller items now for sale, they'll be more profitable than one big plug-ugly monster that requires mountains of materials.

I've finally found a method of casting that suits me. I'm female, so usually start out doing things like a man would, get depressed that it's so difficult, give up, then cheat and do it the girly way :D

So, for any females out there who are finding the going tough, here's my Patented Method For Female Hypertufers

I have six moulds - I do 2 one day, wrap up and set aside. 2 the next day, ditto, and 2 the next day. Have a day off, then release the 2 that are now 4 days old, and cast into the moulds again.

I'm mixing in very small quantities, and keeping containers separate. So...I measure and mix 1 cement and 2 sand, dry. I'm wetting the vermiculite the night before, and have that in a big bucket in my work-area. Trying to have it damp rather than saturated.

I use a cat-litter tray for the final mixing (a tip I got on this forum :) ). Into the litter-tray I put a heaped shovel-full of the damp vermiculite, and the same of the sand/cement mix. That gives me a ratio of 3 vermiculite, 2 sand, 1 cement (I know that sounds confusing, but it's right). Then I mix together as if making pastry, wearing rubber gloves. I have a container of water with superplasticiser added, and when the materials have been well mixed I add tiny splashes of that water until I have the consistency I want. The first few casts I made with a very dry mix, but that's too much like hard work, so I'm making the mix a bit wetter now - I try pushing a bit up the side of the litter tray, if it holds against the upright side easily by itself then it's the consistency I'm looking for.

Then I drizzle a handful of the mix into the mould, pushing down well with my fingers as I go, making sure to get into all nooks and crannies. Build up that way, not putting too much in at a time.

As the sand and cement are already mixed in the right ratios, I don't have a problem with doing 3 or 4 small mixes for each mould.

Handy hints: I've found it useful to have several different pairs of gloves. One fine pair for oiling the moulds - I use a small baby sponge to apply the oil, let the mould sit for 5 minutes, then sponge out any oil that's puddled anywhere in the mould. Another pair of gloves for measuring out the sand and cement, that pair has to stay dry all the time (I put the sand and cement into a round rubber mortar-bucket, about 18 inches across, got it in local builders' suppliers). I mix the sand and cement using my hands, wearing the dry gloves. Then those gloves come off, and I put my 'final mixing' gloves on for mixing the small wet batches in the cat-litter tray, and filling the mould. I buy gloves that are a size too big, with a fleecy inside (don't know how to describe them - just not the cheapest ones which are plain rubber inside). Tight gloves are difficult to get on and off, plus your hands get all sweaty. I have about ten pairs, and wash a few of them every few days - otherwise they start to STINK.

I know it sounds ridiculous to have so many pairs of gloves, but it makes life easier in the long run. Otherwise you get wet mix all over the mortar bucket that you want to keep dry, or on the handle of the cement shovel, or on the sponge that you use for oiling the moulds - as long as the gloves are big and loose, they're easy to slip off and leave draped in the area where you use them.

Anything else while I'm on a roll...oh yeah, use a different shovel for the cement and dry sand, and never get it wet. I don't know if you have coal-shovels in the US, but that's what I use, see link attached.

Obvious thing is that as soon as you've finished casting, wash the cat-litter tray, shovel and anything else you've used so the cement doesn't set on them. I have several small cardboard boxes about 4 inches square, I put a plastic bag inside and push any left-over wet mixture into that. I'm building up a collection of little square bricks that my sister wants to use in her garden.

That's everything I can think of. I try to find 'the lazy way' to do everything, go for whatever makes things easiest, and leaves the least mess to clean up. I'm sure I'll think of something else as soon as I've posted.

RD --- Most men won't tell you this...but the "girly way" is also known generally as the "smart way". As always, great looking work and many thanks for sharing your expertise.

tango

Running Dog,

First I want to thank you for sharing your tutorial, techniques and pictures of the amazing things you make. You are opening up new vistas on the hypertufa forum and raising the bar in a very good way.

Second, I have a question about your tutorial. Did you apply wax to your master between the french polish stage and the silicone application stage? If so, what did you use? I find myself continually frustrated and baffled by mold making. I make things to cast and then get stuck. Right now I've got a very large clay "head" planter sitting on my kitchen table that I made yesterday and I'm walking around mulling on how to cast her. I think the silicone method will work (I hope!) I just want to make sure I understand the process.

Thanks for any advice you can give...

Deb

Here's a picture of her. The cans are in the top to keep her from toppling forward (she's a little face heavy, poor dear).

Deb

Hi, Deb.
This clay head is lovely. Can you please tell me what kind of clay you use and where to find it? I live in a very small town and unfortunately every hobby I pick up, I have to leave town to find supplies. Does this clay stay wet or does it dry out and get brittle after exposed to the air? I'm not sure what to look for or how to find it, but I want a clay that does not dry out. Thanks so much for your help, and thank you Running Dog for this great tutorial.

Suzan

OK, Deb first, Summerdaze second :o)

DEB - Wow! You've done a great job on the head!

The clay needs to be leather-hard before it will stand the pressure of the silicone method. If it's more or less the same thickness all through it should dry out fairly uniformly so it doesn't crack. So leave it uncovered for a few hours and watch it carefully. The packing in the centre might prevent it shrinking evenly (it shrinks as it dries, that's why it cracks if there are uneven thicknesses in the wall of clay).

Once it's leather-hard brush on the first coat of French Polish very thinly and carefully, and leave it to dry for an hour or so. Once dry, apply another thin coat, then another. The coats will take only about 20 minutes to dry. French Polish is just shellac dissolved in a spirit, so if you can't find French Polish anything containing shellac will do. Look for stuff called 'sanding sealer', or anything shellac-based will work fine.

A 'release agent' sounds a lot more complicated than it is. It's the same thing as oiling a cake tin, or lining it with paper, so you can get the cake out. You don't need anything sophisticated as a release agent for silicone - sometimes I put thin latex (medical) gloves on, rub a bit of vaseline all over them, and then rub the surface of the object with my fingers so a thin layer of vaseline is transferred. Make sure that the oily coating gets into all the crevices, around the eyes etc.. You're aiming for a THIN coat of anything oily, just so the silicone releases easily from the surface. Don't get the surface too oily, or the silicone will just slide off as you try to apply it.

SUMMERDAZE - if you're living in an area where you can't get supplies, then you're better off with modelling or pottery clay. That can be used over and over again. When you've made your model and taken the mould, break the clay up into small pieces, spread the bits out on a plastic bag and spray well with water. Let the clay sit like that for an hour or so, to absorb as much of the water as possible. Then put it all back in a plastic bag, splash some more water on it for luck, and seal up the bag with either the original wire tie, or something like duct tape. Make sure there are no holes in the plastic bag, if there are seal them with duct tape. Two plastic bags are better than one ;) Next time you come to use the clay just knead it like you'd knead bread dough, to get it back to an even consistency for working with. I never use anything but modelling or potters' clay, and the clay lasts for years. You just recycle it all the time.

Hope that helps.

hey runningdog!

I love your work.

I had a question about your response to both Deb and Summerdaze about clay recycling. Is the clay recycling/reclamation on unsealed clay or can clay that has been sealed with shellac be recycled as well?

I came into 40 pound of free clay from the local freecycle
group and am about to embark on my own modelling odyssey. I have no idea what the end product will be, I'll just play til I like what I have available.

Thanks for all the inspiration and information. You rock!

Jo

You can pick off the shellac, or take it off with a vegetable peeler, or recycle the clay and pick out the bits of shellac when you come across them - whatever works best for you :)

Running Dog, Thank you SO much! I'm starting to breathe easier about the process--I was feeling a little panicked. I thought I was running out of time but the clay is still soft. I can finish and dry her slowly in the pantry. Last year I made a greenman plaque out of plasticene clay and made the mold for it out of plaster of paris (no latex or silicone) It was a miracle that I got a cast, but had to break the mold.

Summerdaze, I got the clay from a pottery supply store--it is waste clay (recycled) and only costs $3.00 for 25 lbs. I used the whole 25 lbs., lol and am going to have to go back for more to build up the base and make a dam around the rim.

Deb

Great job Debzone please keep us posted on how she's coming along.
Thanks again running dog for the pics and info.
Debbie

Debbie - if you have access to lots of cheap clay, why not make the head solid? Making it as a shell causes unnecessary problems.

You don't actually need the hollow centre in the clay model, if you're taking a mould just from the outside. You need the outer wall, and a base, then you have room to push the mixture in easily.

PS - you could have made life easier for yourself by running bulky hair down the neck to the shoulders. That would make it easier to pack in the mud, and the mould would be easier to release, AND the final piece wouldn't be so top-heavy. The nun that I've shown a photo of on another thread is very top-heavy, and I have to turn the mould upsided down when packing, to fill the shoulders, then turn right side up to do the rest. I'd never design anything like that nowadays, too much like hard work casting it.

Good points--I had thought of filling the master with sand but there's no reason not to use clay and as you said, it will save a lot of grief.

Live and learn. I will have the same issues packing the base with mud that you do with the nun. Hair would solve the problem but I think the aesthetic on both of them would be sacrificed. I love the clean lines of your nun--her headdress is what makes her so arresting. My head was looking pretty bald and has big ears, hence the bead headdress (I may rework some of that). I didn't want to compete with the "hair" that will be growing out of the top of her head. I'm sure I'll sing a different tune when I'm trying to pack the mold through the neck. Upside-down will probably be the only way.

You've given me a lot of food for thought--thanks for sharing your expertise.

Deb

Hi Ms. Running;
I can't thank you enough for this tutorial. I have 3 plaster of paris projects, all leaves, and I had given up on them. I missed the step of *soapy* water for the silicone. I'd also used Murphy's Oil Soap as a release.
Now I'll use vaseline as a release (on a scrap plaster of paris leaf first). If that doesn't work, I'll try a shellac painted or sprayed on first.
I just checked the closet - I have spray Scotchguard, spray starch, spray black laquer, and spray adhesive! No shellac...
Thanks also for the working template. I use a cement mixer and generally stop after one batch. Of course, I still have a 20 hour a week job, a busy house featuring family, roomates, and my new granddaughter. Still, I have to get rolling with production. And Tuesday will be warm enough to get started again!

Ms. Blooming

blooming - I use shellac only on damp clay. With plaster you could use paint, anything that seals the surface. Once that's dry you can put a release agent of some kind (like vaseline) on the surface.

Running_Dog, thanks for sharing all of your progress with Easter Island Head. Lots of good information here and will become one of those "prized" threads, I'm sure.

DebZone, Wow. She's beautiful. Did you have a model when you did this or was it a creation right out of your head? Very nice.

This is a very old thread, and I probably won't get a reply, but it's so helpful I thought I would ask anyway. How long does the silicone take to cure? I'm guessing you let it dry between layers? Thanks.

I haven't done this for a couple years but it seems like I let it set over night before I put another layer on and when the last layer was dry I pulled it off and used it.

Drying time for silicone depends on humidity and the thickness of the layer. The more humidity you have the faster it cures.

Searching online for information on how to thin silicone, I came across this site again, and find my old thread on the first page! In reply (very belated) to aloyzius...I leave the silicone to harden for about 24 hours before making the casing mould.