A Free Tutorial... Mold making at its best

Blanket mold - pg 5

Congratulations! you have extraordinary will power and have managed to not bother your mold for a full day! OK you've earned your reward.  Remove one board.   Pry up the shell.  Get your first look at how your mold came out.  WOW! You did good. It is perfect!

Do not remove the urethane mold from the model just yet.  Now here's the interesting part.  You can use the HydroCal shell to keep on producing more molds.  Here's how it's done.

Make another mother

  Put the first shell (mother mold) aside for the moment. This hydrocal shell will  for now and ever more be known as the master shell.  We won't be needing it for a while. We are going to make another HydroCal shell and call this one the production shell. This new shell is going to be slightly trimmer than the master shell.  Spray the  outside of the urethane  mold with mold release. 

I have cut the vent and pouring sprues off the urethane and plastered right over top of the mold.  No vent or pour hole will be needed in the production shell.   Notice how the shell does not come all the way out to the frame boards. The production shell was made with the same fiber glass and HydroCal mixture as the master shell. Now remove the production shell and remove the urethane mold from the model.  Put the new mold in the brand spanking new production shell.

This is a view of the of the urethane mold in the new backup shell.  Now  that you have a master shell and the  model still mounted on the board, it might only take you a day and a half to make duplicate molds!   Simply repeat the process to make as many molds as you want.  A person of your cunning could take this idea, build a business around it and make themselves a tidy little nest egg.

Now level your mold

Now that we have created this dandy little production mold and back up shell there's one more thing we have to do.  Before we send our brand new creation off into the world  to perform it's function we have to get it to stand up on it's own, straight and level.  No wobble bottom molds for us!

One method of instilling in our mold a level headed approach to life is to give it a firm plaster foundation.  Start by brushing your marble work surface with mold soap, PAM vegetable spray or mold release.  Since we will be pressing the back up shell down onto a small amount of mounded plaster the spraying of the marble with mold release is essential.  

Whenever you are placing a large chunk of plaster on a small puddle of wet plaster on your marble, the tendency will be for the thinner layer of  plaster to stick to the marble. This is especially true when the attached layer  is to be 1/8" or 1/16" thick.  I have found that the way to successfully create a thin layer of plaster is to spray the marble table top with either Pam or Parfilm release.

When the plaster is set up completely, it will lift right off the marble. Now you know the secret to pouring a very thin piece of plaster. Aren't you glad you stuck with it this far! In essence what you are doing is making the plaster an offer it can't refuse. 

I am going to put two thick piles of plaster on my marble. I will set the mold we just made down into this wet plaster.

So it ends up like this. Put a level on it to get it perfect.

 If the mold is not level, wedge screwdrivers or chisels under the backup shell to bring it to a level position while the plaster is still wet.  Work quickly, tapping down where it's high and raising with wedges where it's low before the plaster stiffens. When the plaster has set up just enough to hold the weight of the back up shell, pull the screwdriver or wedges out. 

Alternate method:

I sometimes use old plaster chips to raise a low side. I insert them into the wet plaster under the mold..  Push them under until it brings the mold up to level.  Leave the chips in the set plaster. They will be cemented in place forever as part of the unit and who will ever know they're there?  I won't tell if you won't!  Trim the new foot you have placed on your back up shell to make it look neat and pretty and you're off to the races.

The High  Falutin' Fancy Extras
Some molds need wooden legs or runners. This is how it's done.

Another method of making a stable environment for your budding young  upstart of a mold is to attach wooden runners to the bottom of the shell.  This is the deluxe edition of level back up shells.

Level the mold first by placing pieces of plaster under it.  Lay boards alongside the back up shell

Dip burlap in mixed White HydroCal.

Run the burlap down the side of the back up shell and over the boards.  Put on several layers. Wrap it all around inside and out. Finish the job by smoothing out the final coat nice and neat.  This method makes a strong professional job and as an extra bonus the kids can sleigh ride on it when they're home from school on snow days.  Dry the production shell the same way you dried the master shell.

Now you have made a production mold from start to finish by using the blanket mold system.  Well actually I have made a blanket mold from start to finish.  You on the other hand  are still reading this article.  But when you do tackle it I'm positive your performance will  be a stellar, five star, Oscar winning, Academy raving success.  When you make your acceptance speech don't forget all the little people who helped  you along the way.

Let's make another just like the other. You can make as many duplicates as you want.

Let's say a couple of months go by. (Did you say it? 'cause I'm gittin' a little hard of hearing), and you wish you had another of those dandy little molds you made from the Plaster Master's excellent instructions. To make duplicate molds fetch up the master shell from out of the root cellar or wherever you stuck it and give it a coat of wax and spray it with mold release.  Spray the model with release.

Clean up the side frame boards. Repair the fillets and place the master shell back in it's old home between the frame boards.  Make sure that everything that needs wax has been waxed and everything that needs mold release has been sprayed with it. 

 You do not have to make another clay blanket.  That part is over with for this job.  Hallelujah, hallelujah, yahoo,  praise be, thank the Lord.

However, you will have to follow the same clamping procedure, pouring, back up shell making and demolding as previously exhibited by your incomparable dexterity and execution of the principles presented forthwith. ( That means ya  gotta' do the same thing ya did last time 'ceptin for the clay part .)

Congratulations!  You done good.   That was a real work out.  Now -Let's get plastered!