FX-Lab

dragon

Peter Mühlenkamp — Wed, 13 Oct 2010 11:53:10 +0000

This was quite fun to do, a very open brief to make a dragon head - I was basically told to ‘make a cool dragon’ with hints of snake, crocodile and T-Rex. I spent two days refining a core of polystyrene and then spent another two days slapping clay onto it. I made the tounge seperately and added fast-cast teeth.

eye surgery

Peter Mühlenkamp — Tue, 17 Aug 2010 21:02:04 +0000

I have been wanting to make something like this for a while, a fully accessible silicone eye.

before moulding

Peter Mühlenkamp — Wed, 04 Aug 2010 10:20:59 +0000

Your first question should be: Do I need a mould? Don’t get me wrong, but for example when you’re making maquettes or one-offs, then you might not need to mould at all. There are heat curing materials such as Sculpey or Fimo, there are two part clays such as Miliput and then you could sculpt with NSP or wax-based clays that go reasonably hard once cooled and stiffen up after a while when left alone, there is winterstone culpting compound or you can easily carve into cured plaster if it is kept moist. All of the above can be coloured and could also be moulded at a later date, should you want to. Just saying – if you don’t need to make a mould, then don’t! A copy will never be as good as the original, it will take you much longer and cost you to reproduce your original.

Next question is: What will I be casting in? Well, there a as many answers to that as there are materials, you may even want to cast in porridge – fine, as long as you know before you start moulding. Basically you will have to know: Is my cast going to be hard or flexible? If your cast is going to be hard, you may want a flexible mould – if its flexible, you can get away with a solid mould (normally quicker and cheaper)

Then: You need to keep an eye on the properties of your chosen casting material.

What does it stick to?
Do I need to see inside the mould while casting?

What contaminants are there?
How runny is my casting material?
Will it be laminated, solid, injected or swivelled?

(the places that sell your materials may know and I recommend calling them, describe what your planning to do and they may be able to advise you on the best material/release agent/pigment/special needs of that material)

If you are moulding for money, also keep an eye on efficiency – the most expensive part of the mould is your time! Yes, most moulds I make could be done so much nicer, but they don’t need to be, they need to be super accurate, on few occasions the need to last for quite a number of casts, but thats it!

Then you need to keep an eye on the size of your object – this has quite an impact on how to mould it.

for most small items (up to 30cm) I would only use one moulding material – make a blockmould either from rubber or resin or plaster, if you need extra stiffness use some durable tubing or box that you can put your mould back into for casting. Superfast to make, for bigger items too material-consuming

For most regular sized items (up to 2m) I recommend brush on rubber moulds – fewest possible seams and the greatest range of materials for casting, good accuracy and fast to make, material-efficient. If you know you will ONLY cast in rubber or want to produce a waste mould (mould destroyed for demoulding) you can make stiff moulds for regular sized items – they are considerably faster to make, a lot lighter(if not made from plaster), cheaper, and (if not made from plaster) more durable.

For most large items (larger than life) I would try and laminate a stiff mould, due to weight and normally the fact that large items have large undercuts and you may need to do many pieces anyways and will also very likely have a laminated positive. One little trick for more intricate pieces is the fact that polyurethane rubber will bond to resin if used as gel-coat, so does silicone if you laminate with epoxy. This enables you to make resin reinforced slates that can be very light since you need very little rubber. This however would be far too time consuming and inaccurate for smaller items.

common materials in mouldmaking

Peter Mühlenkamp — Wed, 04 Aug 2010 09:59:01 +0000

Here is a little summary of the materials I use most - how they are used and what to keep in mind when using them. Please be aware that my safety advices may not be comprehensive and always read the label and comply with the MSDS that come with your materials. Don’t know what a MSDS is? Then don’t tamper with these materials!

Solids:

polyesther resin:

good allround resin, very versatile. Thickened best with CabOSil (fumed silica), dissolved with Acetone (not thinned!), takes many many fillers such as ground bronze for great fake bronzes. Normally comes preaccelerated (blue colour) and needs MEKP hardener, normally around 4% but amount can be varied in accordance to humidity, temperature and thickness. Tends to burn in curing. Pretty brittle. Very smelly- contains Styrene. Problematic with some materials (dissolves polystyrene, addition cure siliconne will not cure against polyesther resin unless thoroughly tempered)

Cheap though! Reinforced with glass fibres.

Long sleeved clothes, Latex/Vinyl gloves, respirators, goggles recommended (especially for handling the hardener – very corrosive and very runny), ventilation!

Epoxy resin:

Much nicer texture, needs some „fast“ and some „slow“ hardener, normally 20% by weight. Less brittle than Polyesther resin, also gives off toxic fumes, but does not smell as much (but let this not fool you!) Generally similar to polyesther, but more durable. Fast hardener tends to burn. Does not cause cure inhibition with addition cure rubber! Does not dissolve polystyrene! Does not pump styrene into your cast. Reinforced with glass fibres, thickened with CabOSil, aluminium hydroxide or glass balloons

More expensive than polyesther

Long sleeved clothes, latex/vinyl gloves, respirators, goggles recommended, ventilation!

Fast Cast resin:

Two part PU based resin, normally 1:1, cures in up to 5 minutes, comes in a great range (in terms of curing time, hard- / brittleness, and runnyness. Normally very runny which makes it a great casting material for intricate pieces. Can be poured or swivelled, thickened fast cast resins make a great resin jacket for moulds. Fine with addition cure silicones, not smelly, does give off toxic fumes. Bonds to addition cure silicone if the two are combined while curing. Thickened best with glass balloons

Long sleeved clothes, latex/vinyl gloves, respirator, goggles recommended, ventilation!

„Biscuit Foam“ - rigid polyurethane foam

Two part PU foam, comes in various expansion rates – the lower the expansion the harder and heavier the foam. The very hard stuff makes a great quick jacket for rubber moulds, the lighter stuff is very useful for reinforcing from within (say you have cast a head in a thin layer of fast cast that would otherwise easily break – foam it and it will be light and durable!)

Long sleeved clothes, latex/vinyl gloves, respirator, goggles recommended, ventilation!

plaster:

I am sure you all know plaster, but: Did you know you get different grades of plaster? Softest is called modelmaking or superfine plaster, then you get dental grade plaster that gets extremely hard (my favourite is called Crystical R) For our uses, I strongly recommend using the hardest one you want to afford, the harder the plaster the thinner you can make your mould – something that you really need to consider with the heavy plaster. Pretty much stick to the recommended mix ratio of plaster/water. Reinforced with burlap (jute fibre) (moisten before adding)

still a great moulding material, non toxic, easy to use, more surface detail than one might at first think. Brittle of course, heavy as f*. Addition cure silicone does NOT cure against plaster, unless waxed to hell and back or sealed.

Dust mask if you are creating a lot of dust, latex/vinyl gloves if you want.

Flexibles:

silicone, condensation cure /tin cure:

two part silicone, normally 10:1, various curing times, great range of hardnesses, cures against almost everything. Shrinks a little, rips easily after about two years, breathes off alcohol. Not suitable for clear casting materials and delicate PUs and addition cure silicones. Not safe to use on skin. No fumes, if degassed and newly cured it is almost indestructable. Bonds very well to itself if clean. Pretty indestructable, uncured silicone can be washed out with white spirit

Long sleeved clothes recommended, latex/vinyl gloves

silicone, addition cure/ platinum cure:

two part silicone, normally 1:1, various curing times, great range of hardnesses, most durable and accurate rubber. Safe to use on skin, does not cure against moist materials or such containing sulphur (clay, plaster, latex) or styrene or some PU-rubbbers or superglue or actually a lot – its a great great material and one of the safest of the above, but please be aware that it is easy to make it not cure correctly and that can be very very frustrating since it is expensive and not just will you have to start all over again, but you may also have to clean up any residual uncured silicone before your second attempt, or it will ‘infect’ your new rubber. Love it very much, it is your friend, but pay attention to your friends needs, or it will turn against you.

Do wear vinyl gloves NO LATEX – the uncured stuff is pretty tacky

Polyurethane rubbers:

from as rubbery as some silicones to „tupperware“-hard, PUs have the greatest range of hardnesses. Two part rubber, various mixing rates, gives off pretty evil fumes, should be degassed, does not like moisture or oxygen when uncured, super easy colouration with alcohol based inks (Copic, Letraset, Tria) best to keep warm after demoulding for post curing and reducing fumes until not smelly… Decomposes quickly, most not very UV-stable.

Long sleeved clothes (very, very sticky), latex or vinyl gloves, respirators, ventilation, goggles recommended

cushion foam – flexible polyurethane foam

two part PU based foam, various mixing rates, different expansion rates – high expansion: Soft and light, low expansion: hard and heavy. Same as rigid foams. Especially the softer ones need vicious beating after they have fully cured to break the cell structure and make them keep their shape. Sometimes the soft foam collapses like a misbehaving cake without any obvious reason. Make sure you stick to the correct mix ratio (you will need super-accurate scales) and mix it very well, even though it may start to rise really fast.

Long sleeved clothes (very, very sticky), latex or vinyl gloves, respirators, ventilation, goggles recommended

block moulds

Peter Mühlenkamp — Wed, 04 Aug 2010 09:42:56 +0000

Quite often I find myself making small block moulds – simply building some walls around the piece I want to mould and then flooding the whole box with silicone. This procedure is extremely quick and most of the times suitable for reproducing a small number of items. The great advantages are time and – depending on the object – hidden seamlines. Sometimes I cut the silicone open to make demoulding easier. Sounds a bit viscous, especially on small pieces, but actually the more ragged the cut is, the better the mould will close again.

Now, with intricate little b*rds, you really want to be able to see whether a) your piece is not hugging airbubbles while moulding and b) the material you are casting in gets into every cavity. There are a variety of good prototyping silicones for that purpose, but I want to talk about two of them in detail.

Rhodorsil 3040

Rhodorsil3040 from Rhodia is a shore A35 platinum/addition cure RTV silicone which is extremely translucent – in fact, it is the clearest I know of. The other advantage of Rhodorsil 3040 is its very slow curing. Normally it takes around 24h for it to cure fully, which allows even microbubbles to rise to the surface and pop, giving you a flawless mould with silicone reaching into the smallest cavitiy.

What I do is after mixing and degassing (although with this stuff not as necessary) is fill the mould and let it sit for an hour or so, after which I can see wheter any bubbles need ‘assistance’ in rising. After I am sure that the mould will be fine, I place the mould somewhere warm overnight, max. 50°C (make sure that you are not melting hot glue or your plastiline scultpure or anything!)

That should speed up the cure and allow you to continue working the next morning

When moulding, I recommend placing your object in a translucent box (acrylic or polystyrene sheets glued together, your old fishtank…) at least something with highly polished surfaces especially the base plate, because once you are filling the mould, the surface of your base-plate is where you are trying to see your mouldsurface through. Do not use superglue to stick your box together as it willcause inhibition to addition cure silicone

If you use say MDF, you will get a very dull surface and even the clearest silicone will be opaque.

If you do everything right, your mould should look like this (not necessarily a frog, though)

A variation of this cut open or half mould is making it two-part. A little more complex, but will look a lot more professional and may be a little more accurate in terms of locating the seamline. It is

also suitable for very hard materials that you wouldn’t be able to cut with a knife.

In this case, embed your piece in clay or plastiline and create a VERY neat seamline. Add keys to taste and accurately insert rod or brass tubing at least the diameter of the bolts you intend to use to close the mould later. Like before, build a box around your piece and flood with your moulding material. Once set, flip the mould upside down, remove the clay and push both the rods and the box up, so you can pour the other side. When finished, clean up the mould and if you are using a rubbery material, its a great idea to wedge the actual mould between two pieces of acrylic or board (if you don’t need to see the inside of the mould – like when using opaque material)

This makes a sly little mould for producing bigger ammounts of the same thing, they are pretty durable and you can mould several pieces at once (which can speed things up severely!)

common mistakes:

bad release (especially with PU), airbubbles, loss of transparency due to bad release/choice of housing, object moving/floating, bad seamlines, overtightening, airbubbles in the cast

migros advert

Peter Mühlenkamp — Sun, 06 Dec 2009 16:47:25 +0000

I finally found the link to the TV-ad for which I made the silicone frogsThis is a TV-ad from the swiss supermarket Migros, where all the animals on a farm let their farmer sleep a little longer. In 2009 I made a bunch of silicone frogs that could breathe and croak. It’s nice to seee them in the finished ad… check it out:

NSP and wax based clay

Peter Mühlenkamp — Tue, 28 Jul 2009 20:10:54 +0000

A Friend of mine just conacted me on melting NSP and wax based clays - All regular plastilines can be liquidised, the problem is - they all remain kind of gooey (all I tried - if you know of one, pleeeease let me know!) - which causes problems if you are trying to reach into every fine detail of a mould. “Autostyle clay light” is a discontinued product, which was a wax based clay with added fillers to make it light and malleable.
There are many light clay like that, like the one from Kolb (except TechClay), or P60 - everyone claims they can be melted and poured, but every kind I tried so far did not get as runny as the Autostyle (runny as double cream) or they separate
However, be careful when pouring NSP or a light clay - don”t overheat, make sure you are wearing appropriate protection (this stuff is nastier than hot glue and people have been SERIOUSLY burned) and make sure your mould is nice and hot to avoid nasty tidelines. You can also use a hot air gun for your first layer and paint the liquid clay into your mould.
if you want to reinforce large pieces, only pour a skin of clay, place a bin-liner in your mould and fill it with biscuit foam - having the bag around it helps the clay to stay free of crunchy bits that the foam creates - also, it makes your cast relatively light…

frogjob

Peter Mühlenkamp — Sat, 16 May 2009 17:17:13 +0000

my most recent little job - quite an entertaining one - a frog that can breathe and croak for a Migros TV commercial I made at Trick-Reich in Berlin. I used Plat-Gel with a lowered shore hardness and inserted three tiny bladders that would allow the little fellows to come to life. Here is the Video

roast human

Peter Mühlenkamp — Wed, 15 Apr 2009 21:25:14 +0000

my recent project was a rather twisted one (yap, even I think so every once in a while) Making a succulent, mouth watering roast human. Well, although I had to go cheap on materials I really enjoyed making this one, because I had a pretty relaxed deadline and could do everything properly. Also, I am going to use some of the pictures I took during the process for some new tutorials, so watch out for new stuff.

painting on silicone I.

Peter Mühlenkamp — Mon, 23 Mar 2009 22:08:49 +0000

One of the great mysteries in this industry (or let’s rather say, everybody seems to have his or her own way - as with so many procedures in this job, but I have come across a lot of people who are unsure how to get a good finish) is the colouration of silicone. Technically, silicone wants to stick to itself, but then again - it does not really. I like using Plat Gel and Tin Gel, but especially when applying Tin Gel in thixotropic layers, it tends to come apart if you left the prior layer to fully cure before aplying the next one.
The ‘non-sticking’ of materials to silicone is a serious problem, but when keeping in mind a few tricks, your results should be good.

tinting

tintig silicone is a lot easier than painting onto it. Quite a few things will work and if it cures, it will not rub off. Silicone pigments are the best to use, I like the ‘Smooth On’ ones for their deep saturation and consistency. Also, the base tones red, blue, yellow and black and white are very ‘clean’, meaning it is easily possible to mix any tone and shade. In addition, I also have the brown and flesh tone on the shelf.
Apart from silicone pigments, you can use oil paints - it works, but I do not really like to use them, the pigments tend to be big and normally the oil paint is too thick and you will have to water them down with some kind of solvent, like white spirit and that will affect the curing of your silicone, especially when you add a lot of paint to your mix. I also like to add some red flock to flesh tones, since it distorts the very even colouration and thus makes it a bit more lifelike.
Basically, try adding whatever you feel like, but try first. Many things may works, others won’t.

painting

there are many ways of painting silicone and every manufacturer seems to have a solution for it. Some people like to use the silicone they used for the cast as a paintbase, but especially with condensation cure silicone that does more harm than good, because it might not cure.
Looking at what a paint is, you have got three basic ingredients: pigment, solvent and a bonding agent.
For pigmenting I simply use silicone pigments
As my bonding agent I use a one part “bathroom sealant” type silicone, Dow Corning 734
It dries quickly and is already nice and runny and it also bonds well to both condensation and addition cure silicone
As a solvent I use something rather special - it is called cyclopentasiloxane and a base to many makeup and bath-products and is one of the few harmless substances in this industry. It does not affect the curing of the silicone, does not smell and evaporates. This stuff can be bought from jacobsons chemicals as “Diluent No.5″ or from Kryolan if you ask them kindly.