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Discussion Starter #1 (Edited)

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Discussion Starter #3 (Edited)
When and Why to make a mold


There are several reasons to make molds. One of the most common reasons is economic.

You want 1 skull? Go buy it.
You want 5 skulls? Is it worth your time?
You want 100 skulls? Gonna save A LOT by making a mold or three.


But, there are also the times when you want something unique, for whatever reason.

Maybe you just want your own look.



Maybe you want to sculpt somthing for a specialized use.



Consider the time investment a mold is going to take (in my experience several days to a week to make a latex mold) before deciding whether it's worth your effort.

Why Latex and other options.

Why latex molds?

For skulls, specifically, I find latex the best option.

Molding latex is easy to find, available at any Michaels (take a coupon) at time of this writing. Larger quantities can be had for cheaper online, but the jar at Michaels is just enough for a skull mold and will run you about $8 with a coupon. http://www.michaels.com/search?q=mold builder

Latex holds details of the model great.
Latex is stretchy, and thus can capture most the skull without showing a seam.
No mold release needed when casting in plaster (which I do for the skulls).
WITH a mold release CAN be used to cast a resin skull.


However, latex also has it's drawbacks:

Stretchy mold can be easily deformed, resulting in imperfect casts. (top right, bottom left, note the funky shape from stretched face)



I've noticed lifespan of the molds significantly reduced when casting in resin
Casting in foam, theoretically possible, I've had absolutely no success.

So, what are some other options?

On the cheap side comes plaster.

Plaster molds are Cheap, fast, and easy. However, you're going to need several pieces.

Myself, I've mostly used them for casting latex pieces, but they CAN make really good plaster or resin casts with a proper mold release. Problem with doing a skull is you'd need 3 pieces, which means seams.

At the other end of the spectrum, there is silicone molds.

Let me be very clear. SILICONE MOLDS are among the best there are, able to cast in virtually any material you want, more durable.

My problem with using silicon boils down to price. THEY ARE PRICEY to make. In a lot of ways you get what you pay for. If you're looking to make things to sell, go silicone. You want the mold to last forever, go silicone.
 

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Discussion Starter #4 (Edited)
Model selection and preparation.

Model selection for a mold is one of the most important steps.

Porous materials should be sealed prior to attempting to make a mold. This includes clay, wood, plaster, etc. A good coat of clear coat will work wonders, but be careful not to lose your detail.

Oil is also incompatible with latex. Any oil based stains on an item need to be washed off. Oil based clays should be avoided.

Once you have selected a model, however, a lot of times some additional preparation is needed.

The skull model used in my latest mold was stained with oil based stains, thus preparation begain with a thurough scrubbing, altering my model's color in the process. But, having bought it specifically to make molds, that was of little concern to me.

The model was also so detailed, little gaps between the teeth were present, and various anatomical features such as the holes for optic nerves at the back of the sphenoid and things were present. This is some kind of wizardry used to reproduce that that eludes me and I leave to the experts, thus I needed to modify the model further. I used DAS clay, packed into the trouble areas. Here you can see it in the back of the eyes, and between the teeth (pressed from the back).



Here, the hollow left by the zygomatic arch is filled in with DAS clay.



An underside view showing the DAS clay behind the teeth.



A previous model I've done is shown here, utilizing PLAYDOH instead of DAS. IT works.



Here, the crystal skull prep is getting model magic in it's eyes.



And under it's jaw (wanting to fill that whole area in the cast)



DAS, Model Magic, and Playdoh, in order of my preference, actually.

The one thing to keep in mind as you are preparing the model is WHERE ARE YOU GOING TO FILL YOUR MOLD?

In the case of my crystal skull, note I chose right behind the lower jaw, and thus prepped the model for it.



Most my skulls, I choose the occipital condyle and up through the vomer (where the neck meets the skull up to the palate structure).

 

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Discussion Starter #5 (Edited)
Primary Mold making

Now that we're prepped, it's time to get to work.

needed:

Mold Builder Latex
Brush you don't mind getting ruined
Cheese cloth
Patience

Optional:
waxed paper
fan
oven
hair dryer



You WILL ruin your brush. I've yet been able to clean one off satisfactorally. Choose wisely.

Simply start by taking your model and brushing a thin coat of the mold builder latex on. I like to start with the skull sitting on the table. A nice thin coat will keep the drying time to a minimum. The latex mostly clears as it drys.

The jar I was using was a little old, and thus thick, and dried swiftly. This presented challenges and advantages, note how some areas are already clear (dry) by the time I finished brushinc and grabbed my camera.



Once this is dry, flip the skull over and do the underside as well. I like to set my skull in a bowl to hold it while doing this. The latex on the top of the skull then acts as a bit of grip so it doesn't roll around on me too.



Once this layer is dry, we'll reverse the process and start the second coat on the bottom. THIS coat we want nice and thick, however.





You're typically going to have to wait a day or sometimes 2 at this stage.

*Optional* Speed drying at this point by utilizing fans, hair dryers (LONG TIME, use a junker), and my favorite method, the dashboard of a car on a hot sunny day. (WILL STINK THE CAR!!!)

However, there is always the OTHER option when you're in a time crunch. THE OVEN.

Now, I like to think that the latex here is required to give off a certain level of odor. Normally it does this in nice little slow pockets over the course of time taking a day or so...

However, if we throw it in the oven, it all comes out at once (and makes lesser being run for the porcelain god). I, myself, have a little roaster oven JUST for these type projects, and dial it up to 175 degrees, plop in the dern thing and check it in 45 minutes.

Presto. Mostly dry, and intensly odorous.



For our THIRD coat, we want to embed a layer or three of cheese cloth into the face and top of the head. This will help keep these critical areas from deforming during casting. However, do not cheesecloth any undercuts (bottom of the mold that is smaller than the widest area, needs to stretch).




After a third, standar coat on the bottom, take note of any weak/thin areas.



Go ahead and apply a 4th coat to those areas. Optionally, you can also forego the use of a mother mold and apply a 4th, and 5th coat to the entire mold at this point. Doing so results in a tradeoff of strength and durability for more risk of breaking casts.

Another horrendously odorous round in the oven, and I had a primary mold.



HOWEVER YOU DECIDE TO DRY, ALLOW THIS TO DRY COMPLETELY BEFORE REMOVAL!!! Tips for removal to come a little later.

We are not removing now, however, as I wanted to create a mother mold.
 

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Discussion Starter #6
The Mother Mold

What is a mother mold?

A mother mold is simply something to support the primary mold. Let it keep it's shape, add strength, etc. NORMALLY, I don't bother with one when doing a skull mold, to be honest, and just accept the deformities that might occur. However, if you are wanting to fill a mold all the way or using heavy casting material, or have a large piece, mother molds become neccessary. For my last project, where I intended to gift the mold from the get go, I wanted it a little thinner than my normal mold thus easier to use, but more likely to warp. That meant making a mother mold.

Anything that is going to add strength can be used!

Plaster? Great.
Plaster Wrap? Great
Duct tape? Sure.
Clay? Why not.

It does not matter!

You're going to want a minimum of 2 pieces on your mother mold. This one is utilizing plaster wrap. Half the head is covered (note I am NOT taking the mother mold into the eye sockets, that could make removal interesting). Why plaster wrap? Cause I get it dirt cheap in bulk.

http://orthotape.com/plaster_bandages.asp

A couple layers of plaster wrap is all that is needed. The ridge down the center is my split point. On finishing this section, I coat that with vaseline so that the next half will separate easy before finishing the other side.



After finishing the OTHER side, you need something to keep the two together. A rubber band, a piece of tape, but I decided to get real fancy like, put some more vaseline on that ridge, and build a little stand that would be convenient for letting a new casting dry.



But, like I've said, ANYTHING works.

For those playing at home, this is model magic clay held in place with electrical tape. I went total redneck on that crystal skull mold...

 

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REMOVAL!

Alright, we've got the mold made, now it's time to get the original out, right?

THIS is the most nervracking part of the whole process, both for getting the mold off the original and off each casting thereafter.

MANY make the mistake of trying to get the mold off too soon, with latex that is not dried and ready.

The easiest way I've found is to start at the back of the occipital condyle (where the neck meets the skull) and roll forward.



As you roll forward, turning the mold inside out as you go, keep an eye on the zygomatic arch, and pull the mold away as it puts pressure there. As the back of the skull comes out, unfold the teeth and palate from the mold, leaving the eyes and nose for last, you should thus finish with an entirely inside-out mold.

Making a New Skull!

Finally, we can get around to what we all come for. NEW SKULLS!

Put your mold back together, making sure the primary mold is seated properly in the mother mold if you're using one. No little wrinkles or divets.

Needed:

Plaster of paris
Water
Stir stick
Measuring cup (sorta)

Optional:
Disposable plastic cup

I don't MEASURE, per se. But, I use a 1 cup measuring cup as my scoop. Just scoop the plaster of paris, nice and mounded, and put it into my disposable cup.

You want to mix the plaster to about the consistency of pancake batter and mix it thuroughly with your stick. There is no precise measurement on how much water this will take, but it's not much.

A note on water:

COLD water will allow you more handling time and take longer to cure.
Warm water can get tricky as it cures faster.


Now, pour your plaster into the mold, and roll around the plaster to coat all sides. START AT THE FACE!. Some tapping and shaking might be needed to get into all edges. Once the mold is coated, set it aside to dry.

Once a layer is dry, you'll want to add a second and third, optionally 4th coat. I find 3 is a happy medium of weight to strength, but 4 is VERY sturdy. Of cours, nothing is preventing you from just filling the mold with plaster either if a hollow skull is not your desire.

***One handy method I've found to know if the plaster is ready for another coat or not is to set aside that disposable cup.*** Squeese the sides a bit, if the plaster pops off, you're ready for another layer. If it just cracks and sticks to the sides, you're not.

It's about 15 minutes for a layer to cure, though temp and humidity can change that.

Allow your final layer to cure for a good 30 minutes before attempting removal, this helps the layers cross-bond. It's BEST to not wait till the plaster cures overnight or some such, however, as the plaster is warm while it's curing, this makes the latex mold a little more flexible and easier to remove.
 

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Coloring Techniques

Now we should be making lots of nice white skulls with our mold(s).



Time to get them a bit more natural looking.

My preferred coloring method is utilizing oil based wood stains, but first, you need to soak that skull in water.



Now, whether you want to brush on, spray on, or dunk to get that stain on is up to you. I like little spray bottles, but there are even spraypain cans of wood stain these days.

But, spray a little stain on.



And smear it around.



Bonus points if you get your face.



Walnut, Mahogany, and red sienna, from darkest to lightest.



Once dry, a good way to keep your skulls from cracking is to seal them with a clear coat, I like modpodge. You can also fill the insides with great stuff for added protection or to hold them on pikes.

Blacklight skulls

Whenever you're painting for a black light, it's important to start out neutral/non reactive. Unfortunately, plaster or paris is slightly reactive, and that means your first step is going to be some kind of a base coat.

The darker stain varieties work well in this use, as does a wash of a non-reactive paint.

Now, to get the skulls painted, I prefer wildfire paints.

http://www.wildfirefx.com/wildfire_net/Items.aspx?code=WAK&key=cat

The artist kit will go a long way.



Specifically, I like something that is not insanely bright/crazy for my skulls. This means coming up with more muted colors.

Early trials were mixed results.

Pure optical white yields a blueish tinge and early mixtures were too off to one color.




A mixture of Deep Violet, Bright Green, and Brilliant Yellow will yield a tan color under blacklight and a muddy brown under regular light. Mixing this with enough Optical white to get the shade I want in regular light typically doesn't impact the blacklight coloring too bad. Thus more natural looking skulls were born. It was interesting to note the base coat influenced the final look with the blacklight mixture.

IT'S IMPORTANT TO CHECK BOTH LIGHTING IF YOU ARE WANTING A DUAL USE SKULL.

(Note how the eye sockets light up, I've since decided to not paint those for the blacklight skulls)




The latest skull featured a dark grey - blackish mismatch paint watered down wash for a base layer, with the tan mixture dry brushed on top and highlights of pure optical white.






 

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This is one of the most incredible how to's I've seen. Very much appreciated. I do have a question though. Can this be used to cast foam skulls, such as with Great Stuff foam in a can? If so, what release should be used as to not destroy the mold. I realize Great Stuff might not turn out as much detail, but it would be very practical for a lot of applications, pretty cheap, and extremely lightweight. My goal would be to make lots of foam skulls.
 

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Discussion Starter #18 (Edited)
This is one of the most incredible how to's I've seen. Very much appreciated. I do have a question though. Can this be used to cast foam skulls, such as with Great Stuff foam in a can? If so, what release should be used as to not destroy the mold. I realize Great Stuff might not turn out as much detail, but it would be very practical for a lot of applications, pretty cheap, and extremely lightweight. My goal would be to make lots of foam skulls.
Sorry, just saw this.

THEORETICALLY, it could work with a silicone or even dish soap mold release. With 2 part foam, it SHOULD work ...

However, I once tried with great stuff...

The end I sprayed into expanded, sealed, and the inside built enough pressure the rest reverted to liquid till I tried to peel off the mold, then it sprayed all over my arm....I don't think you could create a bigger mess if you tried.

I would strongly recommend SAND casting with great stuff...will dig up the tutorial for that in a minute.
 

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Great tutorial, this is exactly what I looking for to create skulls in bulk for my voodoo theme this year. I've created the latex mold and mother mold out of plaster wrap with no problem. I'm having a lot more difficulty with the plaster of paris casts though. I've done 3 skulls so far and I can't seem to get the thickness right as I've shattered portions of each skull as I remove it from the latex. I've been playing it safe with 4 layers of plaster for each skull, but maybe my plaster mixes have been to thin. Also, I haven't yet been able to get a cast with the front teeth still intact, the 3 front teeth have cracked off each time I try. It makes sense though, since that is the thinnest and weakest point of the mold.

So just thought I'd give an update, I'm still really encouraged by the results, it's just taking a few casts to perfect the process.
 
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