SiliNOT! Testing and Review

a bottle of SiliNOT! mold maker and a mold

Since I run a lot of casting workshops, I’ve had several people in the costuming/maker community ask me my opinion on SiliNOT!, a relatively new product advertised as a budget- and eco-friendly moldmaking alternative to silicone, urethane, and other single-use materials.

I finally bought a couple of bottles to play with, so I did a test project. My experience and findings are below! (It’s not a recipe blog, but if you want to skip the play-by-play and get to the TL;DR, it’s under the big “In Summary” header near the bottom.)

First, if you aren’t familiar with this material, SiliNOT! is a remeltable, reusable medium for making molds. Though its exact ingredients are not disclosed, it purports to nontoxic, food-safe, and compostable. It melts in a household microwave or double boiler and solidifies at room temperature (or in a refrigerator/freezer for faster results). The website is

(I am not an affiliate, and have no connection to this company apart from having made one retail purchase from them. I just have a lot of casting experience and like trying out new products.)

The Positive Original

I’m still in the middle of a Vincent Valentine build, so I decided to test the SiliNOT! on his custom buttons. My original is a stack of various nonporous materials: an antique (probably Bakelite) coat button, an epoxy resin dome I cast using a mold I already had in my library, and some engraved Worbla’s Pearly Art for the raised detail. The button shanks won’t be added until the final casting, so the original can be mounted flat for the moldmaking process.

Sample Worbla on the left; completed button stack on the right:

a hand holding a plastic star and an assembled button

The Mold

I built the mold container the same way I do for silicone pours, with the flat back of the button fixed to a styrene plate and a cylinder (actually a small paper cup with the bottom cut off) surrounding it for the walls. The lip of the cup is sealed all the way around with Monster Clay to prevent leaks.

top-down view of a mold container containing a button

Heating and Pouring

melted SiliNOT!

The SiliNOT! didn’t take long at all to heat up; I did maybe four or five 20-second bursts before it was completely fluid. The bottle does get rather warm, so hand protection isn’t a bad idea. If you have heat-resistant gloves, you can use those; I was working in my kitchen (yay for nontoxic stuff!), so I just grabbed an oven mitt with a silicone grip.

The melted SiliNOT! looks a bit like Luke Skywalker’s blue milk. It’s about the consistency of a yogurt smoothie and likes to pour in a thicker stream compared to silicone. While silicone can be stretched into a thin ribbon for delicate pours or chemically thinned with solvent for really tricky jobs, SiliNOT!’s viscosity is dependent on temperature and never seems to get quite as thin as silicone.

I’d automatically made my mold compact to conserve material (not really a concern with a reusable moldmaking material like SiliNOT!, but after using silicone for more than a decade, I’ve trained myself to be as efficient as possible), so the walls of my mold container were only about half or three quarters of an inch from my object. Because the target was so narrow, I found it difficult to accurately fill from the lowest area of the mold with the SiliNOT! The heavier pour also means more air can get trapped in or under the material.

a filled mold container

Bubbles are one of the areas in which SiliNOT! is decidedly inferior to silicone. SiliNOT! has higher viscosity, so bubbles don’t want to rise to the surface without vigorous tapping, which can distort the mold edges or affect leveling depending on your mold container. The bubbles that do make their way to the surface are difficult to pop, even when poked with a sharp implement. Heat gun degassing doesn’t have much effect.

Since the bubble surface cools and skins over quickly, I actually had to use a tool and scoop some large bubbles completely out of the mold to allow the surface to level. Critically, the SiliNOT! is opaque, so you can’t spot bubbles clinging to the surface of your original. (This is why my first mold was a reject, and I had to repour. More on that below.)


Once the surface had set, I carefully moved the mold into the refrigerator to cool faster. Here’s another area where some types of silicone can have an advantage: I typically use fast-curing Smooth-On products (because I always have random quantities left to use up after our casting workshops), so I rarely have to wait more than half an hour for a silicone mold to cure, regardless of its size or mass.

underside of mold showing original button

When the mold was completely chilled, I removed it from the refrigerator and popped it off the plastic plate I’d used for the base of the mold. The texture was very different from what I’d expected: Unlike other meltable materials (Monster Clay, et al.) that have a firm surface when cool, the SiliNOT! remains tacky, which means it promptly collects any debris that crosses its path. In my case, this meant I had to pick dog hair off the surface throughout the casting process (and I don’t want to think about what would happen if glitter had contaminated the work space).

The SiliNOT! has to chill completely before handling, though, and discharging that amount of heat requires a fair amount of time even in a cool environment. My mold was pretty small, maybe 2 1/2” wide by 1” deep, and it still took around 40 minutes to cool completely. A larger, deeper mold could hold considerably more energy in the center, and might have to be left in the freezer for a couple of hours before use.

Demolding the Original

I’d used a paper cup for my mold walls, which usually works fine with fast-curing silicone. But the SiliNOT! must have a high oil content, because the cup absorbed some of it:

paper mold cup with oil stains

Lesson learned; use only nonporous containers with this stuff.

The SiliNOT!! really wanted to cling to the edges of my original, so I had to go slow at first to avoid tearing the thin flanges of the mold off. However, it did demold nicely from the smooth surfaces, and preserved texture very well. You can see the Worbla pebbling and the engraving channels clearly in the mold (as well as some dust and dog hair, because I made the mistake of setting it down briefly):

Unfortunately, as you can see, a large bubble had stuck to my original and created a pit in the mold, so I decided to do a second mold pour. I figured I’d tear up the failed mold and put the pieces back in the bottle to remelt… and discovered I couldn’t. The mold would stretch and twist, but not tear. It also seemed to return to its original shape relatively faithfully. Here’s a video of me manhandling the mold:

As you can see, the SiliNOT! has much better stretch and recovery than many silicone products (there are silicones that stretch well — some of the Dragon Skin products come to mind — but they’re not typically marketed for moldmaking). This means it’s likely well suited to casting objects with moderate undercuts or oddly-shaped bits that need the mold to stretch during demolding.

You can cut the SiliNOT! easily with scissors, which is the recommended method for getting it back in the bottle when you’re ready to remelt.

Take Two

Using what I’d learned from the first pour, I did the second one inside a hard plastic ramekin. This gave me a bit more room to pour into the floor of the mold, reducing the bubble risk, and also eliminated the porous paper cup that had absorbed oil. I still had the issue with bubbles that didn’t want to pop, but there were fewer of them this time.

ramekin filled with mold material

The ramekin made for a much cleaner mold, buuuuut there was ANOTHER BUBBLE right in the middle of the design. >.<

a mold with the impression of an eight-pointed star

Take Three

Lather, rinse, repeat. Or in this case, melt, pour, chill.

This time I heated the SiliNOT! as much as I dared and did the absolute slowest, narrowest pour I could manage, giving the air extra time to escape as the mold was filled from the bottom. The risk with stringing out the pour like this is that in a thinner stream, the heat escapes faster, leading to uneven viscosity as the liquid fills the mold. I don’t think that’s a major problem for this particular piece, but it’s something to pay attention to as regards leveling and degassing, especially for larger molds that will take longer to fill.

The result of pour three:

a hand holding a mold with the impression of an eight-pointed star

/siiiiigh/ Well, at least the bubbles are smaller, this time. They may not show up enough to matter in the final cast. I’ll give it a try.


I had leftover workshop resin that was getting on toward the end of its shelf life, so I used Smooth-On Smooth-Cast 300 for my initial resin trial. It’s an opaque white resin with about a 10-minute cure time (the fast turnaround is why we use it for workshops).

Before pouring, I had to do a little mold cleanup where the SiliNOT! had managed to sneak under the edge of the Worbla (I think I’d loosened the corner of the star from prying it out of so many molds), but since the SiliNOT! stretches so well, it was pretty easy to invert it to get little scissors down into the bottom of the depression.

For the first cast, I didn’t use anything but the resin in order to get a baseline. Ideally I’d like to cold cast or dye the resin so I don’t have to worry about paint chipping, but since I’m doing a trial here (and need multiple buttons anyway) I figured some plain white extras wouldn’t hurt.

So, my first cast…

a damaged mold
a positive cast with surface damage

…smacked into a big problem, which I probably should have seen coming: The resin I’m using is a fast cure formula, which means it discharges a fair amount of heat as it’s going through that rapid chemical reaction — enough heat to melt the SiliNOT!, as it turned out. When I tried to demold it (after giving it a few extra minutes beyond label time to be sure it was done), the surface of the mold had melted to the resin and even embedded itself in a few places. It’s difficult to see the resin detail in the photos (my camera went into white balance panic mode with all the shades of white and blue), but you can see how pitted the formerly-smooth mold surface is.

In fairness to the SiliNOT!, the bottle does say that you should put the mold in the freezer for half an hour before casting high-temperature materials. But I assumed high-temperature material was something like candle wax or melted chocolate, rather than ordinary resin. (And the mold had just come out of the refrigerator.)

So, on to pour FOUR of the SiliNOT! mold…

Take Four

NGL, this is getting a little old. >.<

Fourth mold definitely needed some cleanup around the edges, and there are still a couple of tiny bubbles I can’t seem to get rid of, but it’s good enough for a test. (I’m starting to despair of using these for actual production, given how many times I’ve had to redo the molds because of bubbles…)

a hand holding a mold

Deep in the recesses of my basement, I found some transparent epoxy resin with a 24-hour cure time — much slower and lower-temperature than the Smooth-Cast. Since it cures clear, I went ahead and mixed in some metallic powder pigment on the off chance that I get a usable button out of this one. I had excess resin after mixing, so I poured that into my first mold, which has a bubble in the design but is otherwise fine. Two test pieces are better than one, right?


Here are the results of the slow-curing resin out of mold #4:

Finally, a (mostly) clean cast!

As you can see, the detail reproduction is excellent — certainly on par with the pulls from the silicone mold I ended up making while waiting on this set to cure (purely for time reasons; I couldn’t afford five days to cast the buttons using slow-curing resin, and with a silicone mold and fast-curing resin I could get them all done within a couple of hours).

However, you can also see a few spots where bits of the SiliNOT! embedded themselves in the final cast. Part of that may be due to design flaw in the original; I didn’t want to glue anything permanently to the antique button, and that resulted in a tiny gap between the button and the resin hemisphere. Silicone has enough strength to resist tearing out in that kind of area, but apparently the SiliNOT! doesn’t. The bits of mold around the outer edge seem to have stuck just to be difficult, as there was no structural reason for those to have become embedded in the resin. This means the mold could be damaged by successive casts, reducing its usable life and accuracy.

Still, the mold definitely produced decent results for a first cast, and a different shape might not have had as much of a problem with tearing off mold parts. The slow-curing resin is a bit of a limitation, but not a unique one (I use this same epoxy resin for any glass-clear casts I do, and only use the Smooth-Cast 300 for opaque items or things I need very quickly). I don’t personally use UV resin, but I’d be curious to learn how it performs with the SiliNOT!


Here’s the TL;DR on SiliNOT!


  • Cost effectiveness. This is the most obvious advantage of SiliNOT! over silicone; it’s (theoretically) infinitely reusable, and even with natural attrition/inevitable contamination from use, you can likely get over a hundred pours out of a bottle. That’s a lot cheaper per use than silicone.
  • Non-toxicity. SiliNOT! is touted as food contact-safe, so you don’t have to panic if you get it on your skin or kitchen counters. While platinum-cure silicone is also relatively harmless (some varieties are labeled for food or life casting), other common moldmaking materials such as tin-cure silicone or urethane are not. (NOTE: Since the company is very hush-hush about what actually makes up the SiliNOT! secret formula, I do not know if it might release any vapors or fumes that would be irritating or harmful to pet birds. In general, I advise not doing any kind of casting around birds.)
  • Eco-friendliness. This is the biggest draw for me personally: Given the number of casting workshops I run and all the things I sell commercially, I have constant guilt about the amount of waste I generate for creative projects. In most areas of life I’m an aggressive reduce/reuse/recycler and try to use organic materials instead of synthetics whenever possible, so a mold that’s reusable and compostable is very appealing.
  • Ease of use. It’s honestly pretty hard to mess this up — just microwave according to the directions and pour. No measuring, no A/B mixture, no concerns about chemical contamination from latex or sulfur, etc.
  • Shelf life. Unlike silicones, which have a shelf life of anywhere from six months to three years depending on storage conditions, the SiliNOT! purports to be shelf-stable. It’s compostable, so don’t bury it in your yard, but otherwise it appears that it could be kept on hand for years.


  • Bubbles. Honestly the most irritating thing about this stuff for me. I’m used to being able to see bubbles forming as I pour, tap them to the surface, and remove them. The fact that I poured four molds of the same object and never once got one without bubbles is super irritating.
  • Stickiness. I’m not a big fan of the tacky surface texture, and while I haven’t done any cold casting yet, I can imagine that it would be very difficult to clean out any pigment or mica powder that got where you didn’t want it. I probably wouldn’t use this for any kind of cold casting that required isolated colored areas or changing colors between casts.
  • Set time. The SiliNOT! may take longer to cool than a fast silicone would to cure when dealing with larger molds, so it’s not ideal for projects with a really tight turnaround. (But cosplayers would never be casting something the night before a con, right? We always plan ahead and never, ever procrastinate!)
  • Library life. The SiliNOT! may or may not structurally degrade over time the way urethane, latex, and tin cure silicones do, but I noticed even in my very limited casts that it was prone to having tiny bits of the mold (particularly at edges) stick and pull off. While I keep most of my platinum silicone molds for years and reuse them, I don’t feel that the SiliNOT! molds would hold up to repeated casting, and they’re far more sensitive to ambient temperature, so they’re probably best used for short term only. (I also wonder about the possibility of oil leaching out in long-term storage.)

Comparative Ranking

Ranking it against other mold-making materials, I’d place SiliNOT! below platinum-cure silicone in terms of performance, but maybe somewhere in the neighborhood of urethane and tin-cure silicone. It’s definitely superior to latex. (Though to be honest, I’d rank Play-Doh above latex. I hate working with that stuff.)

Factoring in cost and environmental impact, it beats out urethane and tin-cure silicone. I’m still not sure if I’d rank it above platinum-cure silicone, though… Silicone costs much more and isn’t eco-friendly, but the performance and lifespan is significantly better, so it still makes more sense for some projects.

Alginate is another type of material entirely, but in some ways SiliNOT! is comparable to it — both are more cost-effective than silicone, both are biodegradable, both are skin safe, and both have long shelf lives. But SiliNOT! is easier to use for beginners than alginate, which has to be mixed to the right consistency and has an extremely short lifespan once poured.

Overall, I would recommend SiliNOT! for:

  • People who want accurate, non-shrinking molds but don’t have the budget for platinum-cure silicone
  • People who are committed to eliminating waste from single-use materials, and are willing to trade off a little performance for a more eco-friendly material
  • Projects with smooth surfaces and no indentations/sharp edges/undercuts where bubbles might stick (e.g. cabochons; simple geometric forms)
  • Projects where you need only one or two casts of something, rather than many casts from the same mold
  • Casting oddly-shaped pieces around which the mold needs to stretch in order to demold
  • Use with slow-curing resins that do not generate much heat

I would NOT recommend SiliNOT! for:

  • Extremely complex or detailed pieces, or pieces with a lot of surface texture that bubbles might stick to
  • Two-part molds
  • Projects requiring many identical casts out of the same mold
  • Molds that you intend to add to your library for future or repeat casting
  • Use with fast-curing resins, melted wax, melted Monster Clay, or any other material that emits heat
  • Cold casting with precise color application

My Overall Opinion

It’s… okay? I will almost certainly keep SiliNOT! in my toolkit for certain specific applications. It’s MUCH cheaper over the long term, I love the idea of recycling mold material, and there are some projects for which it will likely perform very well (those listed in the above bullet points). I will also admit that three days of working with it does not constitute a comprehensive familiarity with the product, and it might be the sort of thing that you get better at working with after more practice. (Just learning how to eliminate bubbles would go a long way toward making me adopt this for more projects!)

However, I don’t quite buy the “better than silicone” tagline. It’s definitely more difficult to get a perfect result, and there are some projects for which platinum-cure silicone is always going to be more reliable (e.g. high-temperature casting, mass production, large-scale life casting).

For those looking for a recommendation of whether or not to buy, I’d say look at your project budget and the applications for which you’re going to be making molds, and let those factors guide which mold material you go with. People doing some kinds of projects are likely going to find this a godsend, while those doing different projects would probably hate working with it.

finished Flynn Scifo shield

Flynn Scifo (Tales of Vesperia) Ultra-Light Shield

This prop was part of a Worbla sponsored build.

Although Flynn carries several shields (ToV is, after all, a JRPG with equippable items!), I wanted to make the most iconic design and the one that, IMO, looked the best with the Commandant uniform I would be wearing. The promotional materials and merchandise often contradicted each other in terms of the costume and prop design, so I decided I’d work only from the game model. I took countless screen captures and FINALLY got the perfect angle showing the entire front design! The back was trickier to capture, but simpler in design, so at least I could extrapolate from partial shots. These are the main images I used as references:

Materials: Due to a spine injury, I have rigid medical restrictions on the amount of weight I can carry, so I needed to make the shield as lightweight as possible. I still wanted it to have the appearance of something solid, so I designed a layered structure that would use thin plastics over a bulkier but lightweight core to give the appearance of weight without the physical mass.

From the back of the shield to the front, the layers are as follows:

  • Worbla’s Black Art
  • 12mm EVA foam
  • 20mil PETG
  • Worbla’s Pearly Art (applique)

Also used in construction:

  • 20mm half-round EVA foam dowel (trim)
  • 2mm EVA foam sheets (edging)
  • plastic handle (recycled from a computer box)
  • adhesive automotive wrap vinyl
  • leather scrap
  • wood putty
  • acrylic paint
  • spray paint
  • Barge toluene-free contact cement

To begin construction, I needed a scale template of the shield. Using screen captures from the game, I mocked up the shield’s outline in Adobe Photoshop, filled it with a grid (to help line up the pieces for assembly), and printed it at 1:1 scale. I then assembled the pieces like a puzzle and taped them together to make a traceable paper pattern. (One page jammed in the printer, so I traced the mirrored edge and flipped it to fill in the gap.)

clear shield plastic

I used the paper template to trace the shield outline onto large sheets of EVA foam and PETG plastic (pictured). With corrugated cardboard layered underneath to protect my work surface, I cut the shield shape out of each material.

paper shield template

Next, I flipped over my template and sketched out the pattern that would be cut out of Worbla’s Black Art for the back of the shield. Since the shield is curved, but EVA foam is flexible, I wanted a thermoplastic sandwich on both sides of the foam to help it hold its shape. There is a large red area on the back of the shield in the game art, so I decided to use Worbla for that section to support the curve.

Once I had the full back panel design sketched out, I reproduced it on some plain posterboard to make another cutting template. The design has a lot of curves, so I traced plates, cans, and other household items to make the circles neat and symmetrical. I traced the posterboard template onto a sheet of Worbla’s Black Art, then cut it out.

Since I wanted to adhere the Worbla directly to the foam, I didn’t want to coat the entire foam surface in paint that might peel off under stress. I traced the Worbla piece onto the back side of the foam, then painted only the area that would show around it.

Choosing a paint color was a bit tricky. The game sprite is composed of solid-color polygons, but flat color looks a little odd in real life. Since I was using metallic gold accents on the main part of the costume, I wanted the shield to match visually, but I still wanted to preserve the bold ochre tone of the shield trim. After testing several color combinations, I settled on a base of Americana acrylic paint in Antique Gold (first coat pictured) to give a strong yellow undertone, then added a layer of Delta Ceramcoat Gleams in Metallic 14K Gold to add a metallic surface sheen that would match the other costume elements.

To cover the rough cut edge of the EVA foam, I cut 2mm craft foam into 12mm wide strips, glued them around the perimeter, and painted them to match. I filled in gaps between the foam pieces with a small amount of wood putty.

tracing on adhesive vinyl

In the game art, the front of the shield is a rich metallic blue, and for that I wanted something with more color depth than ordinary paint. I ordered a variety of samples of automotive wrap vinyl and finally settled on VViViD+ V203 Matte Metallic Blue (Ghost). I laid out the PETG piece I’d cut using my shield template, cut around it with a couple inches’ overlap at the edge, then applied the adhesive vinyl to one side of the plastic sheet. Then I trimmed the excess vinyl and used Barge contact cement to glue the PETG sheet to the front side of the EVA foam.

I painted several 20mm half-round EVA foam dowels with the same ochre/gold combination as the back of the shield, then shaped them around the edge of the vinyl-covered PETG sheet and glued them down with Barge cement.

training curve using canned goods

Now it was time to give the shield its curve. Using a heat gun on low setting (to avoid damage to the vinyl), I warmed the EVA foam back and the PETG front and gently bent the shield down the middle. To brace the material as it cooled and set, I wedged the edges between many pounds of canned goods so it could not flatten out. I left it there for a couple of days to train the material into a permanent curve.

I took the piece of Worbla’s Black Art on an outdoor field trip and painted it with two coats of Rustoleum Painter’s Touch UltraCover in Satin Claret Wine. Once it was dry, I cut out two small rectangles and inserted a thin plastic handle (which I scavenged from the cardboard box my laptop came in) to serve as the hand grip for carrying the shield.

I coated the handle base, the back of the Worbla piece, and the back of the now-curved shield in Barge contact cement, then glued everything down. (Reminder: Use chemical adhesives in a well-ventilated area!) Bending the EVA foam before applying the back piece ensured that the foam would remain compressed beneath the Worbla, further reinforcing the curved shape. I also used a little heat on the middle part of the Worbla to thermally set the shape.

glowforge cut test

Now it was time to cut the applique for the front of the shield. Because of the complex curves, I decided to try laser cutting the design. (It could also be cut using a Cricut or Silhouette machine, a CNC cutter, or just cut out by hand with scissors. Use what you have available.)

While I had cut other varieties of Worbla with my Glowforge Pro, I had never cut Worbla’s Pearly Art, so I first made a test strip, cutting the same design at seven different settings to see what speed and power level would work best. Ultimately, I settled on a cut speed of 395 at full power. This cut the plastic cleanly with minimal slagging of edges (though there is a tendency at any power level for the melted edges to fuse back together, so some pieces require a bit of punching out).

cut design layout

I generated a vector outline of the shield decoration using Adobe Photoshop (a lot of manual tracing and pixel cleanup) and Adobe Illustrator (to convert the shape to a vector format). Since the design is too large to cut on the Glowforge’s 12” x 20” bed, I had to use the Pro passthrough slot, which allows continuous cutting of longer materials using an automated photo-registration system.

This is where I encountered a novel problem: Worbla’s Pearly Art is white and somewhat glossy, so it reflected light in such a way that the Glowforge’s onboard camera could not “see” the previous cut lines to register the next phase of cuts. This meant I had to manually calibrate each set of cuts, which was a bit nerve-wracking and resulted in some imperfect transitions. However, the material is forgiving enough that I could trim and smooth those edges in such a way that the transition lines are almost invisible in the final product.

glowforge cutting

Most of the cuts went smoothly, however, and the end result looked much cleaner than if I had attempted to cut all those intricate curves out by hand! I don’t know if it ultimately saved much time, considering how long it took to generate the vector outline, but this method was certainly kinder to my fingers.

To attach the applique to the front of the shield, I again used Barge contact cement, since my tests had shown that the Worbla would not adhere firmly to the vinyl on its own. To apply the cement to the small applique shapes, I used a fine chisel-tip paintbrush. (Note: Barge cement will not fully come out of paintbrush bristles no matter how much solvent you use. Do not use your good paintbrushes for this.)

After the applique, I did a few spot touch-ups with wood putty and paint to fill in any gaps that had appeared around the foam seams.

attaching leather strap

The final step was attaching an arm strap to the back of the shield. No strap is visible in the game art, but one is necessary for wearing the shield on my arm, so I wanted to incorporate it into the design as seamlessly as possible. I had a remnant of leather belt flat that turned out to be the exact width of the rectangular sections of the red Worbla design on the back of the shield, so I lined it up and attached it with more Barge cement.

finished Flynn Scifo shield

The finished shield is 28” x 20” and weighs in at just two pounds – well within my weight limit!