Featured Product: Poly 74-20 Polyurethane Mold Rubber

April 16th, 2014

7420 Barkman Stone Veneer 030With so many mold rubber options available, we like to feature individual products from time to time. Perhaps you’ve skipped over the product in the past, not knowing that it could be a great option for your application.  In “Featured Product” blogs, we go over the general characteristics of the rubber, physical properties (e.g., mix ratio, Shore Hardness, pour time, etc.), and popular applications. As always, please reach out to our technical support staff with any questions you have.

General Characteristics of Poly 74-20 Polyurethane Rubber:

  • The softest and most flexible Polytek® polyurethane rubber.
  • Low viscosity (800 cP). Other Polytek polyurethanes start at 1,200 cP.
  • Pourable or brushable (with the addition of Poly Fiber II thickening agent)
  • A great option when working with models with deep relief and undercuts – this rubber offers flexibility to demold parts without damage.
  • In many cases, a release agent is not needed when casting wax, plaster, and concrete in these molds. Resins can also be cast in molds made with Poly 74-20, but the use of a release agent is necessary.


Physical Properties:

Poly 74-20 Mix Ratio Shore Hardness Pour Time Cured Color Mixed Viscosity Specific Volume
1A:2B A20 30 minutes Yellow 800 cP 27.5 in³/lb

Poly 74-20 rubber can be demolded after 16 hours and used with care after 24-48 hours.


Popular Applications:

Veneer Stones

Poly 74-20 rubber is most often used to make veneer stone production molds.

Veneer Stone Mold

Corner Stone Mold

Polytek Venner Stone Mold 3

Veneer Stone Demolding

Watch the making of a Poly 74-20 veneer stone mold:


Decorative Design – Perfect for Delicate, Deep Relief Patterns

Decorative Concrete Molds

Decorative - Rubber Molds

Decorative Concrete


Sculpture Reproduction

Sculpture Reproduction Mold

^One-Piece Cut Blanket Mold with Mold Shell

Dog Sculpture Mold

^One-Piece Cut Blanket Mold with Mold Shell

Poly 74-20 Brush-On Mold

Brush-On Mold

 ^Brush-On Mold [Poly 74-20 Rubber + Poly Fiber II]

Rubber Block Mold

^Poly 74-20 Poured Block Mold

Two-Part Poly 74-20 Mold

^Two-Piece Poly 74-20 Poured Block Mold

Small Sculpture Mold

Watch the making of a Poly 74-20 Block Mold:



Poured Block Molds for Automated Demolding

Mold Rubber for Automated Demolding


Trial Pricing & Free Shipping

If you have never ordered Poly 74-20 directly from us before, you can try it at a discounted “trial” price and receive free shipping (in the contiguous US).


Let’s Talk About Your Project

Not sure which rubber will be the best option for your mold? Ask us:
Call Us at 800.858.5990
Email Us at sales@polytek.com.
Fill out this simple online contact form.


Body Casting Tutorial: Hydrogel® Mold & Cold Cast Bronze Casting

April 9th, 2014

Body molds and castings can be made using a variety of products. The following tutorial details the steps needed to create a Hydrogel® body mold and a cold cast bronze body casting.


Step One: Apply Hydrogel® to Model

Position the model (the ropes, pictured in Figure 1, allow the model to hold her arms in that position more comfortably) and carefully apply Hydrogel® Mold Compound.

Hydrogel is a white powder that, after mixing with water, cures in approximately five minutes to a moist, rubbery material. Hydrogel is skin-safe and is useful for making quick, single-use molds. A variety of casting materials, like plaster, wax, and some polyurethane resins, can be poured directly into Hydrogel molds.


Hydrogel Mold Compound Polytek


Apply the first layer of Hydrogel very carefully to avoid entrapment of air. After application and cure of the first layer, apply a mixture of baking soda, water, and food coloring [Figure 1]. Food coloring helps to ensure thorough coverage against the white hydrogel, while the baking soda and water help to adhere the second layer of Hydrogel to the first layer.


Hydrogel Body Mold

Figure 1


Apply the second layer of Hydrogel. Overall, the thickness of the mold should be approximately 1/4″.

Add cotton batting to the second layer of Hydrogel [Figure 2 & 3] so that the plaster mold shell (constructed in Step Two) will have fibers to adhere to. When the second layer of Hydrogel cures (~5 minutes), remove excess cotton and prepare the plaster.


Body Mold Hydrogel - Cotton Batting

Figure 2

Hydrogel Body Mold - Preparing for Plaster Shell

Figure 3


Step Two: Make Plaster Mold Shell

Create a hard outer shell to support the soft Hydrogel mold.

Carefully apply plaster bandages over the Hydrogel (another option might be the use of plaster and burlap) [Figure 4].


Body Casting - Plaster Mold Shell

Figure 4


Step Three: Make a Plaster Casting

When the plaster mold shell has cured (the total mold making process took us approximately one hour), carefully remove it from the model [Figure 5].


Life Casting Mold

Figure 5


Immediately pour plaster into the Hydrogel mold; this needs to be done right away as Hydrogel molds dry out very quickly and become unusable.

When the plaster has cured, remove it from the Hydrogel mold [Figure 6] and retouch the casting as necessary (at this point, the Hydrogel mold is no longer needed).


Body Mold and Plaster Casting

Figure 6


Step Four: Make a Rubber Mold of the Plaster Casting

After retouching the plaster casting, a long-lasting rubber mold can be made.

We chose to use Polygel® 40, a self-thickening polyurethane rubber, to create this mold (NOTE: Polygel® 40 is no longer available – Polygel® 35 has taken its place). Polygel 35 has a mix ratio of 1A:1B, a working time of 8-10 minutes, and demold time of 8-12 hours.

Apply a relatively thin first layer of rubber in order to pick up detail and avoid air bubble entrapment [Figure 7].


Brush On Mold Body Casting

Figure 7


Apply layers of rubber until a mold thickness of at least 1/4″ is reached [Figure 8]. Always allow the previous layer of rubber to gel before applying the next one.


Polygel Brush On Rubber

Figure 8


If necessary, add PolyFiber II (a thickening agent) to Polygel to create a thicker rubber for filling undercuts on the casting.


Rubber Body Mold

 Figure 9


Allow the rubber to fully cure before moving on to the next step.


Step Five: Make a Two-Part Plastic Mold Shell

Construct a shim (cardboard and duct tape are used here) and registration marks (clay and rubber are used here) to align the two halves of the mold shell [Figure 10]. Apply a sealer (e.g., paste wax) to the cardboard shim to avoid bonding of the plastic. Also apply a release agent (e.g., Pol-Ease 2300 Release Agent) to the shim, rubber and clay to avoid bonding.


Shim for Two-Part Shell
Figure 10


Mold Shell Material: Combine Poly 1512X polyurethane plastic and Poly Fiber II (a thickening agent) to create a plastic with a brushable consistency [watch a video tutorial of creating a mold shell here: http://youtu.be/3sVc2U_-LNM].

Brush-on one half of the mold shell (to where it meets the shim) and allow it to cure (approximately 30 minutes).

NOTE: Cured plastic can have very sharp edges, so consider sanding down the edges before handling the mold shell.

Remove the cardboard shim, apply a release agent to the exposed cured plastic and rubber and then brush on the second half of the mold shell and allow it to cure. [Figure 11].


Two Part Plastic Mold Shell

Figure 11


When the mold shell is completely cured, drill holes through the parting line so hardware [e.g., nuts and bolts) can be inserted in order to secure the two pieces together for casting [Figure 12].



Figure 12


Step Six : Cold Cast Bronze

The mold is now ready for casting. To create a cast bronze effect, use a combination of EasyFlo 60 polyurethane resin, Bronze Powder, and PolyColor Brown Dye [Figure 13]. EasyFlo 60 has a mix ratio of 1A:1B, a short working time of 2-2.5 minutes, and a demold time of 15-30 minutes.


Cold Cast Bronze Kit

Figure 13


Spray and brush out Pol-Ease® 2300 Release Agent onto the mold before pouring the resin mixture.


Rubber Mold Life Casting


Use the following volume ratio to create the cold cast resin:

By Volume:

1 Part EasyFlo 60 Part A

1 Part EasyFlo 60 Part B

2 Parts Bronze Powder


Thoroughly mix the resin and brush it into the Polygel® mold. Because of EasyFlo 60′s short working time, it is important to work relatively quickly.


Cold Cast Bronze Slush Cast

Brush On Cold Cast Bronze

Bronze Resin Casting


After allowing the mixture to cure for approximately 15-30 minutes, apply another layer of EasyFlo 60 plastic and PolyColor Brown Dye as supportive backing (we did not use bronze powder in this layer).


The Final Cold Cast Bronze Body Casting

When the resin is completely cured, remove it from the mold and hand burnish it with steel wool to expose the metal particles. Additionally, a patina can be applied (not pictured here).


Cold Cast Bronze Body Casting


Video Tutorial

Watch this video tutorial to see Hydrogel® being used to make a hand mold:


Would you like to speak with a Polytek Technical Support staff member about your next life casting project?

Call Us at 800.858.5990.
Email Us at sales@polytek.com.
Fill out this simple online Contact Form.

Or leave a comment right here on the blog!

Tek-Tip: Perform Platinum Silicone Test Cures

April 2nd, 2014

Out of the entire Polytek® product line-up, platinum-cured silicones (PlatSil® products) are most likely to suffer from cure inhibition during the mold making process.

PlatSil 73-20 Silicone Rubber

PlatSil® 73-20 Silicone Rubber, Part A & Part B


What is Cure Inhibition?

Failure of a compound to cure against a surface within the recommended cure time.


How Do I Know Cure Inhibition Has Occurred? 

The surface in contact with the model remains gummy or uncured. If other areas of the mold, aside from the surface touching the model, are uncured or gummy, it may be a different problem: off-ratio measurements or mixing issues.

In some cases, it’s difficult to tell how platinum silicones are going to react to certain materials. Here are some examples that we know cause cure inhibition (when liquid platinum silicone is poured over or into these materials):


  • Sulfur-based clay
  • Tin-cured silicone rubbers (e.g., TinSil® Series)
  • Polyurethane rubbers, in most cases (e.g., 74-Series & 75-Series)
  • Latex rubber
  • Some paint products
  • Some 3D printed plastic materials
  • Bondo (and other polyester resin products)


Perform a Test Cure to Avoid Wasted Materials

The best way to avoid wasted rubber is to perform a test cure on the model material before pouring the entire mold.

Here is how we test it:

Form a small clay circle (with sulfur-free, oil-based clay) on the surface of the model:


Pour the rubber and allow it cure. In this example, we are using PlatSil 71-10, a fast-curing platinum silicone.


When cured (make sure to check the “demold time” of your PlatSil® product) remove the sample and check for cure inhibition:



Sealer & Release Agent Matrix

Our sealer & release agent matrix [pictured below], located on the last page of our Sealer & Release Agent Selection Guide provides a general guideline as to what release agent or sealer is needed for a certain application; cure inhibition is also addressed in some cases.

ReleaseAgent Chart Polytek


Do you have a question about your upcoming mold making project?

Call us at 800.858.5990.
Email us at sales@polytek.com.
Fill out this simple online Contact Form.

Or leave a comment right here on the blog!

Mold Making & Casting Seminar & Workshop: March 2014

March 26th, 2014

Two to three times a year, we hold a mold making & casting seminar/workshop at our facility in Easton, PA. Our most recent workshop finished up last week.

Attendees are invited to bring their own projects (there is a size limitation) to work on over the course of the two-day class.

This is a sample of the projects that were brought:


Mold Making and Casting Workshop Projects


The first half of Day One is the seminar portion of the class – attendees are introduced to the Polytek product line-up (e.g., polyurethane and silicone rubbers, polyurethane plastics, epoxy resins, polyurethane foam) and a variety of mold making and casting techniques (e.g., block molds, brush-on molds, rotocasting, blanket molds, plastic and foam casting, cold cast bronze, etc.).

After breaking for lunch, there is a group review of each project. At this point, Polytek staff members identity which mold product and casting product would be most appropriate for the project at-hand.

Then it’s time for attendees to get started on their molds! Here are some pictures of that process:


Mold Making & Casting Workshop

Mold Making & Casting Workshop

Mold Making & Casting Workshop

Mold Making & Casting Workshop

Mold Making & Casting Workshop

Mold Making & Casting Workshop

Mold Making & Casting Workshop

Mold Making & Casting Workshop

Mold Making & Casting Workshop

Mold Making & Casting Workshop

Mold Making & Casting Workshop

Mold Making & Casting Workshop

Mold Making & Casting Workshop

Mold Making & Casting Workshop

Mold Making & Casting Workshop

Mold Making & Casting Workshop

Mold Making & Casting Workshop

Mold Making & Casting Workshop

Mold Making & Casting Workshop


On Day Two of the workshop, attendees finished up their molds and began casting:


Mold Making & Casting Workshop

Mold Making & Casting Workshop

Mold Making & Casting Workshop

Mold Making & Casting Workshop

Mold Making & Casting Workshop

Mold Making & Casting Workshop

Mold Making & Casting Workshop

Mold Making & Casting Workshop

Mold Making & Casting Workshop

Mold Making & Casting Workshop

Mold Making & Casting Workshop

Mold Making & Casting Workshop

Mold Making & Casting Workshop

Mold Making & Casting Workshop

Mold Making & Casting Workshop

Mold Making & Casting Workshop

Mold Making & Casting Workshop

Mold Making & Casting Workshop

Mold Making & Casting Workshop

Mold Making & Casting Workshop

Mold Making & Casting Workshop

Mold Making & Casting Workshop


To see some of the projects that were worked on at our October 2013 workshop, visit this blog entry.

Our next workshop will be held on October 16th and October 17th, 2014. More information can be found on our website, or:

Call us at 800.858.5990.
Email us at sales@polytek.com.

Tek-Tip: Understanding Physical Property Specifications for Rubbers & Plastics

March 20th, 2014

Our Mold Making & Casting Manual & Catalog is full of technical specifications. They often appear in large tables, like this:

Physical Properties Table Polytek

The EasyFlo Series (Liquid Plastic) Physical Properties Chart

This information can be overwhelming for those that don’t have much experience with rubbers and plastics, so we would like to outline the general meaning of each specification:


Mix Ratio

Mix Ratio Specifications Polytek

The great majority of Polytek products are two-part systems: Part A & Part B. The mix ratio indicates the amount of Part A and Part B needed relative to each other. When these two parts are mixed together at the proper ratio, they cure at room temperature. It is imperative to stay on-ratio to ensure a successful cure – off-ratio mixes can result in subpar final products or mixes that do not cure at all.

Two-Part Silicone Rubber - Polytek

Mix ratios vary from product to product, even within the same series (e.g., The EasyFlo Series).

In some cases, you will find that two different mix ratios are given: one by weight and one by volume.


Shore Hardness

Shore Hardness Polytek

The hardness of our rubbers and plastics are measured on Shore Hardness Scales. The device used to measure hardness is called a durometer.

Rubbers are measured using the Shore OO Scale and A Scale. Very hard rubbers and plastics are measured using the Shore D scale. The higher the number, the harder the material.

Mold rubber hardness scale


For more information on Shore hardness scales, read this dedicated blog entry, or watch the following video:


Pour Time

Pour Time Polytek Products

Pour time, listed in minutes, is the amount of time you have, after adding Part A and Part B together, before the mixture cures to a point where it is no longer able to flow. Ideally, the product should be mixed and poured into a mold or over a model in half of the pour time. The EasyFlo Series, which is featured in the table above, has some of the shortest working times of all Polytek products.

 Poly 74-20 Polytek Polyurethane Rubber


Demold Time

 Demold Time Polytek

Demold time, listed in either minutes or hours, is the amount of time you should wait (starting at the end of the pour time) before removing a casting from a mold or before removing a mold from a model. This does not mean that the mold is ready for use (for casting) at this point. For instance, polyurethane rubber molds do not obtain final cure properties for up to seven days; however, molds can typically be used, with care, 24 to 48 hours after demolding. Demolding or using the mold too soon may deform it.

 Polytek Silicone Rubber


Specific Gravity

Specific Gravity Polytek

Specific gravity indicates how much more or less dense the product is compared to water. Water has a specific gravity of 1.00 gram/cm³. Products with a specific gravity greater than 1 are more dense than water; products with a specific gravity of less than 1 are less dense than water.


Cured Color

Cured Color Polytek Rubbers and Plastics

Cured color is the color that the product naturally cures to; some products are transparent and some are opaque. In many cases, the cured color will not always be the same in individual products (e.g., the kit of 75-Series polyurethane rubber that you’re using this month may not have the same cured color as the kit you order 6 months from now). Part Bs of certain products (i.e., aromatic products) darken with age, resulting in a darker cured color.

Cured color can be changed with the use of PolyColor Dyes (for polyurethane products) and SiliColor Silicone Pigments (for silicone products).

Polyurethane Color Dyes


Initial Mixed Viscosity

Mixed Viscosity

Viscosity, listed in centaPoise (cP), is the resistance of a substance to flow. For example, water has a lower viscosity than molasses and flows more easily.

In this case, the Initial Mixed Viscosity is the viscosity of Part A and Part B once they are combined. The EasyFlo Series, featured above, has some of the lowest viscosities of all Polytek product lines.

Two Part PlatSil® Silicone Rubber

Here are some examples of the viscosities of common materials:

Water: 1 cP
SAE 30 Motor Oil: 500 cP
Honey: 10,000 cP
Sour Cream: 100,000 cP
Peanut Butter: 250,000 cP


Specific Volume

Specific Volume

This specification identifies the number of cubic inches occupied by one pound of material (in³/lb). This number is necessary to determine how much rubber or plastic is needed to occupy a given space.

Specific Volume Calculation


Maximum Exotherm (°F)


This specification is generally only listed for Polytek polyurethane and epoxy resins – it indicates the maximum amount of heat (°F) generated when curing. There will also be a note indicating the mass of the sample used in determining this number.


Other Specifications

Not every product has the same list of specifications and some Technical Bulletins include additional physical property information. If you have questions about any information listed on our website, in our catalog, or on our Technical & Physical Property Bulletins, please reach out to us.

Call us at 800.858.5990.

Email us at sales@polytek.com.

Fill out this simple online contact form and we’ll get back to you.

Or leave a comment right here on the blog!

Celebrating St. Patrick’s Day with Resin Casting [Beer-Filled Mug Replicas]

March 14th, 2014

ResinCastingPolytek - Beer Mugs


For St. Patrick’s Day this year, we used EasyFlo Clear Liquid Plastic to make replicas of beer-filled mugs. This resin casting project makes great decorations for restaurants, bars, and parties.

Here is what you’ll need to make these:


CAUTION: Polyurethane plastics (like EasyFlo Clear) will produce exotherm, so it is important to exercise caution especially when working with glass mugs or containers as cracking can occur.

Step One: Spray Release Agent into the Mug [OPTIONAL]

If you would like to remove the plastic from the mug [picture on left] once it has cured, release agent should be applied to the mug or cup before pouring the resin. Make sure that the mug that you choose has enough positive draft to remove the casting. You might consider using a paper cup so you can cut the cup away from the casting. If you intend to keep the plastic in the mug or container [picture on right], a release agent is not necessary.

Beer Resin Castings

Pol-Ease® 2300 Release Agent is a suitable option if one is necessary:



Step Two: Mix EasyFlo Clear Casting Resin (scroll to bottom to read about adding colored dyes)

EasyFlo Clear is a two-part polyurethane plastic. It has a 1A:1B mix ratio by volume (100A:90B mix ratio by weight) and needs to be thoroughly mixed.

This liquid plastic has a 2 – 2.5 minute pour time, so it’s important to work in a timely manner. Determine the amount of plastic you will need based on the size of your mug – remember to leave space at the top for foam (added later).

EasyFloClear LiquidPlastic


Step Three: Pour Mixed EasyFlo Clear into Mug

Once poured, allow this EasyFlo Clear mix to cure for 5 to 10 minutes before adding the “foam” mix.



Step Four: Make Foam from EasyFlo Clear and Water

Polyurethane plastics are moisture-sensitive and will foam when in contact with water (normally, we would recommend deliberately avoiding water when working with these materials). To make the foam, mix the EasyFlo Clear in the same manner as the last batch (1A:1B by volume or 100A:90B by weight) and then add 50% water and mix.



Step Five: Pour Foam Mixture on top of Cured EasyFlo Clear

The foam mixture will expand, so ensure that there is enough space to accommodate that expansion at the top of the mug.

After pouring, allow EasyFlo Clear to cure approximately 15-30 before handling it.




EasyFlo Clear can be Colored using PolyColor Dyes

PolyColor Dyes can be added to EasyFlo Clear to achieve different colors. We used Green PolyColor Dye and Brown PolyColor Dye to achieve these looks [below]. Dye options include black, brown, blue, green, yellow, red, and white.



Video Tutorial

Watch a video tutorial detailing the process:

Share your casting projects with us on social media: Facebook, Twitter, Google+.


For more information on Polytek® casting materials:

Call Us at 800.858.5990.

Email Us at sales@polytek.com.

Fill out this simple online Contact Us form.

Or leave a comment right here on the blog!

Casting Foam in Polyurethane Rubber Molds

March 4th, 2014

Use Silicone Rubber (if you have it available to you)

Ideally, silicone rubber molds should be used when casting polyurethane foam. Silicone is often preferred because release agent is not required during the casting process (adding a barrier coat or paint can extend mold life, however).


Primed Mold Foam Casting

 A silicone mold (TinSil® 80-30) being primed for foam casting.
Watch a foam casting tutorial (using a silicone mold) here: http://youtu.be/fR8WWkOo8aI

Perhaps polyurethane rubber is all that you have in-stock, or you don’t want to spent the extra money on silicone rubber. There is a solution that will make your polyurethane rubber mold act like a silicone rubber mold: PolyCoat Semi-Permanent Sealer & Release Agent.


 PolyCoat Release & Sealer Polytek

 PolyCoat Semi-Permanent Sealer & Release Agent


Create a Silicone “Coating” on Polyurethane Rubber Molds

PolyCoat Semi-Permanent Sealer & Release Agent is a low-viscosity, silicone-based liquid that can be applied to cured polyurethane or silicone molds (it can also be applied to original models before pouring liquid rubber over them during the mold making process).

PolyCoat can be brushed or sprayed onto the mold (use a Sure Shot Atomizer for spraying). Once applied, it takes about 5 minutes for the solvent carrier to evaporate and about one hour to cure, leaving behind a thin coating of silicone. The cure time of PolyCoat will depend greatly on temperature and humidity of the workspace and may take longer than one hour.

When casting polyurethane foam, it is recommended to apply at least two to three layers of PolyCoat to the cured polyurethane mold. Ensure that each layer is thoroughly dry before applying the next layer.

Once PolyCoat has been applied to the polyurethane mold, there is no need use any additional release agent. This is especially advantageous if the cast foam parts need to be painted. Paint will not adhere to cast parts when release agent is present and removing release agent from castings can be difficult; the application of PolyCoat eliminates these painting issues. PolyCoat even allows the application of a barrier coat or paint (after PolyCoat has been applied and is cured) to increase mold life and produce pre-primed parts right out of the mold.


Internal Testing

Tests performed at Polytek have shown that over 100 rigid, pre-primed polyurethane foam castings can be made from a polyurethane mold (mold product: Poly 74-55) with a PolyCoat coating.


Decorative Foam Castings-01

This polyurethane mold (on the left), coated in PolyCoat, rendered all of these rigid foam castings


Do you have a project you would like to discuss with a Polytek® Technician?

Call us at 800.858.5990.

Email us at sales@polytek.com.

Fill out this simple online “Contact” form.

Or leave a comment right here on the blog!

The Wildlife Casting Project

February 26th, 2014

Sarah Madigan is a wildlife rehabilitator, educator, and creator of the Wildlife Casting Project. Making a wildlife casting is essentially a two-step process: 1) making a mold of a part of an animal (e.g., paw, wing, foot) or an entire animal and then 2) pouring a casting material into the mold to create a copy. Sarah has both state and federal permits for her casting process.

Rooted in devotion to wildlife conservation and awareness, Sarah describes the goal of the Wildlife Casting Project:

My deepest hope for my own work is that as people encounter the animal casts, their wonder and imagination for the wild world will increase. I believe that wonder leads to love, and there is no question that we care for and protect what we love. I will continue to exhibit the wildlife casts and provide conservation groups with materials for outreach and public education programs [...] As a whole, the wildlife casts stand as documentation of our natural history and my way of paying homage to the wild world.

Many of Sarah’s castings are being used in New Mexico schools to educate children on wildlife conservation issues.


The Rare and Endangered Species Trust

One of Sarah’s latest endeavors, which involved a vow to make wildlife castings of all 23 species of vulture in the world, led her to the Rare and Endangered Species Trust (REST), located in Namibia, Africa. REST is a non-profit organization founded in 2000 by Maria Diekmann. The group is devoted to the rehabilitation, conservation, and research of the “Forgotten Five” (plus one!). These animals include: the Cape Griffon Vulture [photo below], Dwarf Python, African Wild/Painted Dog, Cape/Ground Pangolin, Damara Dik Dik, and Spotted Rubber Frog. For more information on this organization, visit their website: www.restafrica.org.


Wildlife Casting Project
Cape Griffon Vulture at REST – picture provided by Sarah Madigan


While in Namibia, Sarah encountered a diverse range of animals and made castings of the following species:

  • The Tawny Eagle (Aquila rapax)
  • The Giant Eagle Owl (Bubo lacteus)
  • The Southern White-Faced Owl (Ptilopsis granti)
  • The Yellow-Billed Kite (Milvus aegyptius)
  • The Wild Donkey (Equus asinus)


These African wildlife castings will be used as educational material as well as part of an upcoming endangered wildlife exhibit. Sarah’s wildlife castings have also inspired future conservation projects, including a return to Africa for a larger mammals project.


A Gift from Sarah

Sarah graciously sent us a casting she made of a jaguar’s paw (Panthera onca – a black panther) [picture below). For this particular casting, Sarah used PlatSil® 73-25 silicone rubber mold material and gypsum cement casting material.

At times, she also utilizes EasyFlo 60 Polyurethane Plastic as a casting material; this plastic can be used in conjunction with brown PolyColor dye and bronze powder for a cold cast bronze effect.


Panther Paw Casting



Have you completed a similar project? Tell us about it in the comments section of this blog or on our Facebook or Twitter pages!

Would you like to discuss your next casting project with a Polytek® Technical Support staff member?
Call us at 800.858.5990.
Email us at sales@polytek.com.
Fill out this simple online “Contact Us” form.

Updated Polytek Labels & SDSs: Meeting the New Hazard Communication Standard

February 21st, 2014

You will notice changes to Polytek’s product labels and Safety Data Sheets (SDSs) as we work to comply with OSHA’s revised Hazard Communication Standard.

Polytek Updated Part B Label

Updated Polytek SDS-01-01


2012 Revision of OSHA’s Hazard Communication Standard

In 2012, OSHA revised its Hazard Communication Standard to align with the United Nations’ Globally Harmonized System of Classification and Labeling of Chemicals (GHS). The revised standard requires new labeling elements and a standardized 16-section format for Safety Data Sheets (SDSs), formerly known as Materials Safety Data Sheets (MSDSs). GHS labels and SDSs are intended to help improve workers understanding of the hazards of chemicals in their workplace and harmonize label and SDS requirements around the world. For chemical manufacturers, GHS labels and SDSs must be complete by June 2015. That might seem like a long time away, but we’re already working hard to ensure that Polytek product labels and SDSs meet the GHS deadline. So, over the next year or so, you will notice new labels and SDSs.


New Hazard Pictograms

The new hazard pictograms are the most notable elements of the GHS labels. The figure below shows the symbol for each pictogram, the name of the pictogram and the hazards associated with each pictogram. Some of the symbols are the same as those used to convey hazards in transportation, but these pictograms are for worker safety, they do not replace hazardous materials labels for transportation.

Hazard Comm. Standard - Labels and Pictograms-01

Not all Polytek products will be classified as hazardous under GHS (e.g., PlatSil,® Silicone Rubbers); those products will not have a pictogram on the label.


Label Requirements

The image below is an explanation of Polytek’s new GHS labels. If you have additional questions, please call! We’ll be happy to tell you more about GHS (contact information below).


GHS Labelling Requirements - Polytek Labels-01


Do you have questions about our new product labels or SDSs?

Call us at 800.858.5990
Email us at sds@polytek.com.


Helpful Resources

OSHA BRIEF: Hazard Communication Standard: Labels and Pictograms
OSHA’s Hazard Communication Web Page

Tek-Tip: Keeping Your Workspace Clean (When Working with Liquid Rubber)

February 11th, 2014

When you work with liquid polyurethane and silicone mold rubber on a regular basis, you come to realize that spills can happen and that cured rubber can quickly accumulate in your workspace…on your floors…on your work benches…and on your tools. And then it can be quite difficult to clean up (especially polyurethane rubbers).

Here at Polytek®, we try to avoid accumulation by taking some proactive steps. These are a few of them:

NOTE: Some of our methods include the use of flammable solvents; always consult safety professionals and review product Safety Data Sheets before incorporating solvents into your process.

Wax Paper – Keeping Table Tops Clean

We keep our shop tables covered in wax paper (taped securely to the ends of the tables). Unlike silicone rubber, polyurethane rubbers are capable of adhering to a wide variety of materials (unsealed wooden tables, for instance) – they do not adhere to this wax paper, which is why we really like it.

Of course, this wax paper will have to be replaced every so often.



UHMW Polypropylene Workbench – Keeping Table Tops Clean

As opposed to wax paper, which must be replaced from time to time, Ultra High Molecular Weight (UHMW) polypropylene is usually a one-time investment. We use it as a table top for our work bench because polyurethane rubbers do not adhere to it and it has high chemical resistance.

UHMW Bench Top-01


Melamine-Laminated Particle Board – Keeping Table Tops Clean

We often use melamine-laminated particle board as a baseboard for mold making projects because cured rubber is fairly easy to remove from this material during clean-up.



Plastic Sheets – Keeping the Floor Clean

We use duct tape to position plastic sheets on our floors - specifically in areas where rubber is frequently mixed. These sheets need to be replaced from time to time.



Solvent Dispensing Cans – Keeping Tools Clean

We have solvent dispensing cans situated in a few areas in our workspace – we use solvents, like denatured alcohol, to clean rubber off of mixing tools (note: it is much easier to clean mixing tools immediately after mixing, as opposed to when the rubber has cured). These dispensing cans provide a convenient and effective way to clean tools.

Solvent Dispensing Can


Containers of Solvent – Keeping Tools Clean

When polyurethane rubber has cured on mixing tools, we soak them in denatured alcohol in a small pail (this pail is a high-density polyethylene material) with a hole in the lid (the hole is only large enough to accommodate the handles of the mixing tools).

Cleaning Mixing Tools


Clear Tape on Scales – Keeping Equipment Clean

We use gram scales quite often in our shop and they see quite a bit of rubber. That is why we apply clear tape to the face of the scale – we simply remove it and replace it when too much rubber has accumulated.

Gram Scale


Pol-Ease® 2300 Release Agent – Keeping Equipment Clean

To prevent polyurethane rubber from sealing containers or valves, we often apply Pol-Ease® 2300 Release Agent (a silicone-based release agent) or Vaseline® to the inside of packaging caps and oil gate valves (on drums of liquid rubber) when they are not being used.




Reusable Polyethylene Pails

Many of our products come packaged in high-density polyethylene (HDPE) “pails”. We also often use these pails as mixing containers.

One of the reasons we use these HDPE pails as mixing containers is because they can be reused (thereby eliminating waste). Once the excess mixed rubber has cured in the pail, it can be pulled out. If there is any remaining material after the cured rubber has been removed, we carefully clean it with denatured alcohol.

HDPE Pails_Reusable-01

What other proactive steps do you take in your shop to help reduce rubber build-up? Leave a comment and let us know!

Would you like to discuss your next mold making project with a Polytek® Technical Support staff member? Call us at 800.858.5990. Email us at sales@polytek.com. Fill out this simple online “Contact Us” form.