Friday, August 26, 2011

Making a Moulage Mold

Moulage is a heat reversible gelatin that sticks to virtually nothing, so it's the almost perfect mold making material. The problem is that it needs to be applied hot and you can't cast much more than wax and plaster into it. Just the same, we find that because of the fact that it is reusable, it is economical and fun to use.

Will last indefinitely if you don't let it dry out. And of course you're not limited to using Moulage just for life casting. Use it for any kind of simple mold making where you don't need a permanent mold, and all you need to cast is plaster or wax.  (from http://douglasandsturgess.com product description)




DO NOT let aluminum come into contact with moulage.  It apparently causes a chemical reaction and can ruin the moulage.  I might actually test that one day out of curiosity.



In an ordinary double boiler, enameled preferably, place the desired amount of Moulage.

I didn't own a dedicated double boiler for my moulage so I placed canning jars of moulage into a large pot (or stock pot).  The pot should be tall enough to allow you to add enough water to cover most of the jar.  At least be able to have enough water up to the height of the moulage that is in the jar.  Do not fully submerse the jars.

* DO NOT use aluminum pots.
** If you plan to use a double boiler, there is no need to place the moulage into canning jars. The moulage would be placed directly into the top pan while the water sits in the bottom pan. My assumption is you don't want the moulage to be in direct contact with the heat.

Heat until melted and the consistency of thick batter. Work out all lumps with a spatula. If too thin, cook with cover off. If too thick, add water.

I brought the pot to boil then set the stove to low.  At the high point the water reached 165F before I set the stove to low.  When I mixed the moulage after it was heated, most of the chunks had dissolved.  Add additional water as needed to create proper consistency.

* I put enough water in a jar that contained new never used moulage to almost cover the moulage entirely.  Since the chunks of moulage were small, the amount of air space in the jar is small.  In my jar of reused moulage I hardly put any water in.  Since the chunks are bigger there is more air space for the water to fill.  So you can't judge how much water you put in simply by water level because the size of the moulage chunks determine how much space there is to be filled.  How much water you add is something you are going to have to get a feel for on your own.
** Since I was using canning lids, I took the band off and left the lid on.  Never cook a jar that is air tight.  The jar can shatter.  You can also leave the lid off when cooking moulage, but more water will evaporate and will require more to be added.  On the same note, if you added too much water leave the lid off to help the excess evaporate.  If you don't want the water to evaporate, keep the lid on.
*** A spatula is probably better than just a stirring utensil.  The spatula will allow you to smash chunks and help them melt quicker.  When I didn't use a spatula, there were tiny chunks in the moulage when I poured.  This, however, did not affect my moulage mold.
**** I do NOT suggest using metal utensils in a hot glass jar. Defiantly no aluminum utensils.


Point to Ponder

On the DickBlick.com site it says:  Just heat Moulage slowly in a double boiler to 115°F (46°C).

On medium stove setting (5) it took over half an hour for the water to get up to 165F in my large pot.  By this point much of the moulage was melted sufficiently and the temperature brought down for the remainder of the time to low stove setting (2) which was still put the water at 130-140F.  So if I slowly heated the moulage to 115F (stove setting 1?)and never went over 120F, how long would it take to melt the moulage?  Is it really necessary to stay at a low temperature and slowly melt the moulage?  When you cook the moulage at a higher temperature , it melts quicker.  Is this a problem?


While your moulage is cooking, you can prepare the molds you plan to make.

No preparation of the object is necessary, except in the case of very porous surfaces.

I used plastruct to create a mold shell for the moulage to be poured into.  (Cardboard is another option.  Although I wonder how undesirable it is to use a material that can soak in moisture.  Not only because of durability but because it might wick moisture from the moulage?  Some cardboards, like cereal boxes, have as slick surface that might be better.)  You can create a multi-part mold if desired, but you will have to wait for one side to set at a time before making another.  I sealed the bottom of my mold shell with oil clay.

* Make sure to seal all holes and cracks in your mold shell.  If they are large enough the moulage will just pour right out.  Some cracks may be so thin that only a small amount of moulage will pour out and stop when it sets faster than it can flow, thus plugging the crack.  Don't rely on that though.
** If you are making a multi-part mold make sure to make the keys on the first part.
*** Although a moulage mold is more flexible than a plaster mold, still be aware of undercuts and where air can get trapped.  Moulage is more forgiving of undercuts, but it does not mean you can ignore undercuts all together when making a multi-part mold or where you make the parting cuts in a one piece mold.

Apply the first coat of Moulage directly on the object with a Moulage brush. If on a living subject, allow to cool to about 100 F. Be careful to brush the Moulage into every corner and irregularity to insure a perfect mold, Air bubbles are prevented by vigorous brushing of the first coat. If making a large mold, cover the depth of about 1/2", then reinforce with course cheese cloth laid in the hot Moulage or with course wire screening and then with another layer of Moulage. Do not allow one layer to cool before applying another. After the first coat has been applied with the brush, it is usually easier to apply the further coats with a spatula or Moulage syringe. Work as rapidly as possible, being careful to cover all parts of the object to the same depth.

The instructions above doesn't seem to apply much to what I am doing.  But it is good to know you can let it cool to 100F without it completely setting.  In some applications, it may be feasible to brush moulage onto your mold.  For most of my uses, I just pour the moulage into the empty space of my mold shell.  I would let the moulage cool down to 105-115F prior to pouring.  At that temperature range, the original sculpts made of oil clay or carving wax are not harmed when making a moulage mold.

* The first time I made moulage it still have tiny chunks when I poured it into the mold shell.  This did not affect the mold quality at all.  So don't freak out if you notice tiny chunks when you pour.  But try your best to get it all melted prior to pouring.
** The jar of melted moulage is not too hot for me to hold at 105-110F.  Your sensitivity may vary.

After object has fully cooled, remove the mold VERY CAREFULLY. Where there is an undercut it may be necessary to slit the mold after removal, close such slits and seal with gauze and hot Moulage. With two or three-piece molds, cut in irregular line with spatula so the parts can be fitted together accurately. Then bind together with gauze and seal with hot Moulage. You can correct small defects in the mold with hot Moulage carefully worked in. Your mold is now ready for casting.

It takes a while for the moulage to cool and set.  (At least an hour for 1/2" thick parts?)  Even a plaster mold takes over an hour to set so be patient.  The thicker and larger the moulage mold is, the longer it will take to set.  Once the moulage is set, it is cool to the touch and rather slick.  So handle carefully.  Pry 2 part molds apart carefully.  They tend to stick together because of the layer of water between them.  If you have a one piece mold, you can make irregular cuts so that it will help realign the molds.  Another option is to cut using a key mold knife.

* The first time I made a moulage mold, I put it in the fridge to set.  I thought this would save me time but I was wrong.  You will need to let your mold get back to room temperature if you plan to pour carving wax into it, otherwise you get poor results.
** It is a good idea to just lightly cover your moulage mold with plastic wrap while waiting for it to set so it does not get too dry.
*** You can pour carving wax into the moulage mold several times with no problems.
**** The larger the moulage mold is, the more likely you will need a material to help support the sides of the mold.  You can use coated smooth cardboard pieces (such as cereal boxes).  It is probably preferable to use something that will not wick a lot of moisture out of your moulage mold, thus drying it out quicker.  Whatever you use, keep in mind moulage can be slick.  You don't want to accidentally drop your moulage mold into a pot of hot wax because it slipped out of the plastruc shell when you tried to pour the excess out for a hollow core.  Hot wax splashing out and onto you is dangerous.  And the you have to figure out how to get your mold out of the wax pot.  Another option is to pour excess hot wax out of the mold into another container and NOT into the hot wax pot.
***** Rubber bands or other elastics can be used to help keep cut sides together, but it can cut into the moulage mold if it is directly on the moulage.

Your first cast from the moulage mold may be a junk cast when pouring hot carving wax.  After the first one the mold is warmer and will be much better.  There are a few factors I learned while casting carving wax into the moulage molds.
1.  Support the sides of the mold if it is too flexible.  When you pour hot wax into the moulage mold, it will push outward.  If this outward pressure can cause the mold to bulge, I suggest making a support to prevent that from happening.  Use cardboard or anything stiff.  Hold together with tape or rubber bands.  If your moulage mold distorts when you pour hot wax in then so will your final cast.
2.  Do not disturb the moulage mold right after the hot wax is poured in.  If the wax inside is still warm and flexible, you can inadvertently cause imperfections from squeezing or even tapping your mold.  You only need to leave it alone until it hardens enough.
3.  Pour hot wax uninterrupted.  Don't pour hot wax into your moulage mold then stop and pour again.  This will create pour lines.
4.  If you plan to cast your wax hollow, you need to time things just right.  In the case of small items, you may need to pour the hot wax in and then pour it right back out in 5 seconds.  The cooler the moulage mold the quicker the pour out needs to be.
5.  If you made a one piece mold and you made cuts to the moulage mold, imperfect cuts or bad ones can affect the quality of your wax cast.  There will be times where a once piece mold will be just fine and other times where a multi-part cast would have been better.

Keep Moulage can well covered to retain moisture. Moulage can be used over and over, but be sure to remove all particles of plaster or you will have hard lumps. Always add water when re-cooking Moulage and be sure to work out all lumps. Allow any Moulage left over to cool thoroughly, then cut into very small pieces and replace in the can and cover tightly, if you wish to keep a mold, wrap it in a damp cloth and keep damp. Do not use moulage too hot. Be patient and remember you're learning an art, and it cannot be acquired without some effort, practice and careful application.

You can make multiple casts of carving wax in the same moulage mold, but it is not suggested to keep the moulage mold for long term storage.  The concern is with shrinkage when the moulage mold loses some of its moisture, thus not able to create a copy close to the original in size reliably.  So plan to use it after you make it.  When you are finished with your moulage mold cut it up and store in air tight container for future use.



When it comes to making and using a Moulage Mold, EXPERIMENT!  It is reusable and the experience you gain even when the results are less than setlar can help you make a better mold the next time.  The Carving Wax is also reusable.  The only thing you lose is time, but it is not a loss but an investment if you used that time to learn something new and how to do things better.  Moulage Molds and Carving Wax are great materials to use.

Resources
FX Supply Moulage Instructions - Source of the blue italic instructions in this post.
Douglas and Sturgees Moulage Data Sheet
Atelier de Poupee  - The blog of the person who introduced me to moulage and has been a great resource to me.  I posted a link the moulage posts if you are looking for some more information.

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