Portal plates: Mold making takes forever!

Portal plates: Mold making takes forever!

While playing a go-to nostalgic (and let's face it: amazing!) video game, I was struck with an idea for a plate based on the primary mode of transportation: portals. Much like plates, portals are round, so I knew right away that I was on to something!

The Mudroom is already set up to make molds for slip casting, so, how hard could it be?!



Well, even if life wasn't full of necessary diversions and indulgent distractions, mold making is a pretty lengthy process. When you get it right on the first try it goes something like this:

After gathering any inspirational materials, sketching a few ideas, and stretching out your fingers, you rough out a model in the right size and shape, exaggerating any details that are going to be important.

From there, refining the form is critical, every little detail you put in (or leave out!) will show  in every single subsequent casting. So the next step is all about smoothing the clay together without leaving unwanted tooling marks. During this process we add what will be the gate (the opening that allows us to fill the plaster mold with slip) and mark up our seam lines. 

Now that our model is everything we hoped for, a fragment of perfection itself, we can get to making our plaster mold. Using a filler material along with a modularly built container of cottle boards and the marked seam lines: the first portion of plaster mold can be poured. 

With an open pour mold, you would be finished. For a two part mold, you're in the home stretch. For anything past that, you're just warming up! Our aforementioned piece of crystalline transcendence is a reasonably simple two-parter though, so, after generous and patient applications of sealant and release (lubricant that keeps our mold from becoming a brick) we can reassemble our containment field and pour our second side of plaster.

Woohoo! We have a mold; let's make some art! ....or:

From this point, there are several choices to be made. How many castings are needed? Infinite? Is the model a vision of sublime idealism? Yes? Great! After a two week curing time for the plaster we can prepare to make the mother mold!

Maybe it needs tweaks or color and marketability testing? Perhaps its just the one-off for personal use and we're ready to get casting in clay? Great! After a two week curing time for the plaster we can prepare to play in clay!

Plaster is 41% water upon being mixed, and for the best clay casting, it ought to be as close to 0% as possible. That way, capillary action can accrete clay to the mold's surface. That amount of water would also negatively affect any sealants, release agents, and could even complicate working with the mother molding material; since plenty of drying time has passed though, this mold is ready to encase in rubber.

Even though silicones come in a variety of types and urethanes have an equally robust catalogue, we can gloss over that selection process. No matter the choice of mother mold material, our model (now the plaster mold, keep up), needs to be sealed. The surface of plaster is, microscopically, like an ocean of Grand Canyons; or very craggy and prone to hold on to things in any case. 

A release agent is a lubricant that helps to keep surfaces from binding, and, in the case of plaster at least: we can use petroleum jelly as both our sealant (imagine paving over an ocean of grand canyons), and our release agent.

Rubber can be poured onto the model now, but it would be unwise. Without a container, the rubber would just run off the sides, onto the table, and likely all the way onto the floor. Here, it's worth building a dedicated frame that accommodates the rubber and the mold neatly; because wood shares a similar affinity for bonding with liquid rubber, a sealant and release should be applied to all faces of the container, even those not expected to make contact with the sticky stuff. 

The edges were pristine, no leakage occurred, bubbles... what bubbles?! After unmolding (excellent release!) and trimming (knife so sharp!) this mother mold is ready to birth as many plaster molds as needed. Though each new plaster mold needs to completely dry and cure before making any clay castings, every mold could be cast, potentially at least, every day.

Once our plaster molds are dry, putting them into action isn't quite instantaneous. Ignoring the demands of production, including maximizing the load potential of an expensive, high-power, commercial kiln, the first item, poured from the first mold will get special treatment. After being poured in the morning, pulled form the mold in the afternoon and cleaned; our casting will need to dry overnight. A final detailing and a day of soaking in fire before a day of cooling to room temperature, and bisque has been achieved.

Applying glaze *can* take as little as a minute, though this ceramic wonder requires more meticulous brushing and, probably half of a day before its back in the kiln. Now that the second firing has adhered our glaze coat we can move on to full out production!


The above is, of course, what we all hope happens when we set out to make. To create with grace and precision in such a way as to dazzle our fans and leave our enemies breathless. For me, it's a fairy tale, but I wouldn't change it to be my reality. Mistakes and problems are an autodidacts best teacher, experimentation leads to new issues which require better solutions. Better solutions lead to better experiments and more interesting problems; and the cycle continues.

If you were counting the days it might take to go from an idea on paper, to a handcrafted ceramic treasure, you could use the above as an outline. At least, that is, for the best case scenario, though, life has a way of challenging our chosen timelines, redefining our goals and changing the outcome of even the most humble ideas.

Join me, Logan, as I share the process and story of making Portal Plate to answer all of your burning questions like: Why has it taken a year? What colors are you gonna make? What's the video game? What's this soap dish I've heard about? Are you really face blind? And more!

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How to make Slip Casting Molds

We are on a journey to create new sculpts & molds. Creating is always an adventure, we are sharing our successes and failures, so others can learn along with us. Unfortunately, our website is not able to host our videos, so we have to share links to Instagram.