Working with Mold Making Latex Rubber

Posted by EnvironMolds , Labels: , , , , , Friday, September 10, 2021 4:45 AM

Latex rubber molds are easy to make, economical, last for years and can be used for multiple castings. Following are a few pointers to be kept in mind when making a latex mold through the brush-on method.

Latex rubber is considered the best material for making molds – it trumps in terms of affordability, durability, reusability, convenience and more. The molds turn out flexible and can be used to capture a negative impression of statues, figurines, plaques, life castings, etc. The most complicated models can be easily captured down to the minutest details.

In fact, latex is formulated in liquid form to allow ease of use for making molds. Take Kreemtex Premium Liquid Latex for Mold Making for instance. The liquid rubber can be brushed, sprayed or poured over the model to capture its shape in a mold. The thick consistency makes it easy to apply and also allows for easy coverage with minimum coats. However, if the rubber seems to be too concentrated, it can be thinned to a more viscous consistency by adding distilled water to get the requisite runniness.

Latex rubber should be stored in a cool place; it should not be allowed to freeze as this will make it unusable. It should be stirred properly prior to use. In case the ammonia content of the latex has evaporated or diminished over time, it is better to replenish the same before use. However, the ammonia should come from a chemical store and not grocery ones as the latter contain more of soap. Add a bit of ammonia at a time till the original texture is obtained.



How to apply?


Brushing multiple coats of latex over the model is the most common method of making a latex mold. Some models may have to be sealed prior to late application. Applying a suitable release agent is preferable.

Start from the top of the model and brush the latex in a thin and even coat while making sure that all air bubbles are brushed out. From the bottom, continue out to form a two inch flange which will serve handy when using the mold for casting.

Allow each coat to dry properly – it should be dry to the touch - before starting the next one. Here it is advised to apply the liquid latex in a checkerboard fashion by alternating the direction of application. This will ensure that the mold does not shrink and the dimensions do not change. A heat source can be used to hasten up the drying between coats.

Once the desired thickness is built up (will take 10 to 12 coats at least), the mold can be removed from the model and allowed to dry further for 72 hours or so. Curing in a warm atmosphere to ensure proper strength and toughness to the mold.

Molds made from Kreemtex Premium Liquid Latex for mold making will be stable, tear resistant and can be used to cast different materials. The outcome will be perfect as long as the proper procedure and precautions are followed!

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How Tough is a Cold Cast?

Posted by EnvironMolds , Labels: , , , Monday, August 30, 2021 7:16 AM

Making a decorative metal piece does not have to be pricey and cumbersome. Cold casting makes it easy, but artists should keep in mind that the reproduction will definitely be more brittle than metal.

Cold casting is a popular method of making faux metal casts. It involves mixing metal powder with a resin to create castings that give the appearance of solid metal. Rather than the hot casting method using molten metal in a foundry that is both expensive and time-consuming, cold casting turns out to be a quick and affordable option for recreating the look of metal casts. There is no risk of burns and other dangers either.

Recreating a figurine, prototype, hardware pieces, small run production pieces and other parts with cold casting is relatively easy. The requisite bronze, brass, copper, steel or aluminum powder is usually brushed, dusted or sprayed on the inside of the mold to form a thin and even coating. Then the resin is mixed and poured into the mold. (For smaller pieces, the powder can even be mixed in the resin itself.)

Once the resin is cured, it is demolded and burnished or abraded with steel wool to remove the binder and reveal the beauty of the metal filler on the surface of the cast. Keep in mind that when the metal powder is mixed with resin, it may take a bit longer to cure.

The same technique can be used to recreate the look of ceramic, wood or even stones like granite, marble and limestone. Tin powder can work well for achieving a pewter, iron or nickel silver finish.



Points to ponder


While a cold cast sculpture will replicate the exact look of the original metal, stone or wood piece, it will obviously not weigh the same. It is much lighter and some artists retain the light feature as it makes the ‘sculpture’ easier to handle. Otherwise the mold can be backfilled with fiberglass, iron or steel shots, sand or calcium carbonate to achieve the desired weight. Alternatively, the cold cast can be lightened by adding hollow glass beads.

Coming to the durability of the cold cast reproduction, it will definitely be hard and durable. The actual toughness will depend on the casting resin used to make the piece. All resins cure hard and epoxy resin is considered exceptionally sturdy. However, the strength and durability of a molten-crafted metal construction cannot be replicated. Therefore, care is required not to bang or drop the cold cast figurine.

The best choice


EnvironMolds offers a variety of fine grade cold casting powders that are 325 mesh grade - the correct fineness for cold casting - and can recreate a beautiful finish. Even the resin options are of top quality and will turn out strong and sturdy castings that can last long as long as they are handled properly.

In sum, cold casting with casting powders is the way to go to get the desired effect without spending a bomb or even bearing the risks of a foundry casting.

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Clay Goes from Modeling to Ballistic Testing

Posted by EnvironMolds , Labels: , , , , , Sunday, August 8, 2021 11:43 PM

Clay is as versatile as a material can get. Get to know the different uses of various types of clay that ranges from clay models, molds and casts to even ballistic testing of vests and varied weapons.

Clay enjoys wide patronage in the world of mold making. Clay modeling is very popular and is used for a variety of purposes. Apart from molds, this extremely malleable substance is also used for sculpting, mask making, special effects, animatronics and claymation. The best part about using Plastilina clay is that it is oil-based and non-drying. This makes the material reusable as well.

Apart from this, clay proves to be handy for various other unexpected uses too. For instance, small dabs of clay are used to affix the model to the base before making the mold. The same clay can be also used to fill the gaps around the edges of the model; this will give a good, clean edge to the mold. Even any spaces or holes in the model can be plugged with clay before applying the mold making material. It also serves well for sealing the edges of the mold box, so that the mold material will not seep out before it cures on the model.


Other types of clay


There is a special type of clay called ballistic clay. The distinct feature of this clay is that it manages to almost replicate the density and viscosity of human tissue. The close match makes it useful for estimating and comparing the destructive effects that various firearms and ammunition can have on the real human body.

The gel like substance is regularly used as a backing material for terminal ballistic testing – like the testing of ballistic vests. It will provide unmatched terminal ballistics data for all types of rifles, handguns, machine guns, muzzle loaders, air rifles and pistols, bows and crossbows. In addition to this, ballistic gel heads and torsos can be used to simulate the effects of various bullet wounds with reliable and consistent results every time.

Where to get them?


EnvironMolds stocks a fine selection of plasticine, ceramic and ballistic clays of all types and price ranges. The renowned choice of professionals – Roma Plastilina clay comes in several degrees of hardness and is suitable for almost any application. Then there are budget options from Del Milano and even sulfur free formulations from Chavant. The latter can be used to cast silicone rubber without any fear of interfering with the setting of the rubber.

Coming to ballistic clay, the art supplier offers ballistic clay and gel blocks along with dummy heads and torsos. The clay is clear, odorless, reusable, 100% synthetic and contains no organic materials. It is non-toxic and can easily be molded into any shape as desired. More importantly, it is completely temperature stable (up to 240℉) too. Moreover, Clear Ballistics does the calibration on the gelatin to ensure that each batch meets the FBI protocols for ballistic testing.

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Learning the Mold Making/Casting Lingo

Posted by EnvironMolds , Labels: , , , , , Monday, August 2, 2021 3:09 AM

What is the negative image of a model called that you will make before making a positive replica? What are the holes on the top or bottom of a mold called? Know the terms that go with molds and casts right away!



The world of mold making, casting and life casting comes with its own plethora of terms and phrases. Familiarity with them is essential.


  • Mold – It is a negative impression of the model, usually in the form of a hollow cavity.
  • Cast – This is a positive duplicate of the model which can be in any other material or color as desired.
  • Cold cast – This is a faux cast – it is made of resin but can duplicate the look of metal, stone or wood.
  • Life cast – The three-dimensional representation of a live person – it can be the face, hands, feet, torso or entire body.
  • Pot time – Also known as working time, this is the time on hand to work with a material – it includes the mixing and application time - before it will start to set. After this, the material will not work properly.
  • Cure time – This is the time that the material will take to get completely cured. It can range from just a few minutes to hours or even a few days.
  • Shelf life - The period of time a material can be stored and remains suitable for use.
  • Mix ratio - The proper proportion (either by weight or volume) of material and catalyst (oftentimes referred to as Parts A and B) to be combined.
  • Shore hardness – This is a measure of the hardness of a given material or how resistant it will be to permanent indentation.
  • Release agent – A material applied in a thin layer to the surface of the model or mold so as to allow the subsequent mold or cast to be demolded easily.
  • Sealer – Another material that is applied on porous models to seal the pores and prevent the mold making material from getting absorbed.
  • Demolding – The process of removing a model or casting from a mold.
  • Parting line – A marking line which denotes where the parts of the mold should meet.
  • Keys – These are created at the ends of multi-part molds to join the different parts together to form a complete mold.
  • Spues – These are the small holes which will help release the air trapped inside the mold.
  • Pour hole – This is created as an opening to allow the casting material to be poured into the mold.
  • Viscosity – This is the thickness or thinness of the material and will dictate how easily it will flow. Less viscous materials are thinner and flow easily.
  • Pressure pot – Resins are usually cast under pressure that will compress the trapped air to miniscule size.
  • Vacuum chamber – The rubber mix is usually churned using a vacuum pump with vacuum chamber. The vacuum chamber will suck out the air and not allow bubbles to appear on the rubber mold or cast.

Armed with this detailed knowledge, get going right away!

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Poured Block vs. Blanket Molds

Posted by EnvironMolds , Labels: , , , , Sunday, July 18, 2021 4:06 AM

Molds can be made by different methods - some simple, others more complicated. Each technique has its own pros and cons and the choice will depend on the preference and dexterity of the artist.

A mold is the easiest way to reproduce just about anything. The mold is nothing but a negative copy of a model that captures all the surface details, right from size and shape to undercuts and indentations. This is used to make original copies that are also known as casts.

How to make a mold can seem quite intimidating at first. However, mold making is actually quite an interesting and fun activity. There are very many materials that can be used to make the mold with an equally varied array of techniques for making the mold. A block mold is the easiest method that is usually preferred by beginners while the blanket molds can get quite complicated at times, especially if the mold has to be made in parts.
 


Following is a look at the primary differences between a poured block mold and a poured blanket mold:


  • Making a poured block mold is quite easy and quick whereas a poured blanket mold can take quite some time and effort. The latter is an intricate task involving making a pour hole and spues which requires some practice to master.
  • Both types of molds call for some form of containment. A block mold is made in a mold box – a suitable container will also suffice here. Furthermore, it is quite easy to make a mold box from scratch too. On the other hand, a poured blanket mold entails the construction of a mold shell. This is again quite complicated, time-consuming and needs practice.
  • Poured blanket molds generally require less mold rubber than poured block molds. It can take three times or even more quantity of rubber to fill the mold box containing the model when making a poured blanket mold. The mold making space is quite restricted (between the model and shell mold) in a poured blanket mold and require very less material. Therefore, poured block molds turn out be much more cost-intensive which can prove to be a limiting factor.
  • A poured blanket mold is usually thinner and more flexible. This makes it much easier to demold a casting from a poured blanket mold than from a poured block mold.

This is why artists usually begin with the block mold method and with practice, move on to the poured blanket technique.

When looking for mold making materials to make either a block or blanket mold, do not forget to check out the array of options at EnvironMolds. The website https://www.artmolds.com is quite a treasure trove for mold makers and casting artists with its massive collection of materials, supplies, tools and equipment for making molds and casts. It even doubles up as a teacher and guide on mold making and casting by offering blogs, books, CDs and other instruction materials choc-a-bloc with handy tips and other useful information.
 

 

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The Best Rubber Material for a Mold

Posted by EnvironMolds , Labels: , , , , Thursday, June 24, 2021 4:38 AM

The making of rubber molds throws up three different options of latex, silicone and polyurethane rubber. Understanding the properties and usage will help in choosing the right rubber for a project.

When it comes to making rubber molds, there are various options, from the natural latex rubber to synthetic compounds like polyurethane rubber and silicone rubber.

One of the first steps when making a mold will be deciding which rubber to use. While each has their own strengths and weaknesses, the choice will determine the process ahead. Let us take a look at each option –

Latex

Latex rubber is one of the least expensive mold making materials. Yet, it is very flexible, strong, durable, tough and tear resistant. It also captures minute details very well. As the rubber is viscous enough to not run off vertical surfaces, it can be applied to models such as architectural details where they are, without needing to be thickened.

Latex molds can be used to cast plaster, polyester resin, urethane or even abrasive materials like concrete. The molds can be used again and again to produce multiple castings. They will literally last forever as long as they are stored properly.

However, it takes a long time (around 10 to 15 days) to make a latex mold. It involves brushing multiple layers of latex on the model, while allowing sufficient time in between for every layer to dry properly.

The rubber works well for creating masks too. Moreover, liquid latex is a theatrical and special effects product used to create wrinkles, scars, gashes and as an adhesive for bald caps.In a less viscous form, the same material will work for casting purposes as a latex casting rubber too.

Polyurethane


This is a high strength rubber with excellent chemical resistance. It opens up options of varying consistencies and even a choice of firmness for the mold – from soft to medium to hard. The cost is on the average side – neither too expensive nor very cheap.

Polyurethane rubber molds are most suitable for casting polyurethane, epoxy and polyester resins. The method of making the mold is not limited to brushing or spraying; polyurethane rubber can even be poured to make solid cube molds. The mold will be ready in a few hours or a day at best.

However, polyurethane molds are not as long lasting and can even lose their shape over time.

Silicone

This is an expensive material, but the superlative properties and ease of use justify the price. It is a versatile, durable and highly resistant rubber with two types of catalysts – tin and platinum – that will affect its working and usage.


The rubber is formulated in varied types with food safe and skin safe options also available. The translucent variant can perfectly duplicate skin surfaces. The best part is that silicone does not stick to anything but itself, negating the use of a release agent.

Silicone rubber can be used to cast different types of materials except itself. Again, the same rubber can be used to make castings too.

Consider all factors of mold making to make the right choice between liquid latex, polyurethane and silicone rubber.

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Types of Silicone Rubber

Posted by EnvironMolds , Labels: , , , , Thursday, June 10, 2021 7:30 AM

There are many basic differences between liquid silicone rubber, room temperature vulcanizing silicone and the high temperature vulcanizing variant which influences their potential use.

Silicone rubber is a man-made elastomer that is composed of silicone with carbon, hydrogen and oxygen. This inorganic rubber-like material is used extensively across various industries - rail, aerospace, automotive, food/beverage and artworks to name a few. The superior benefits of resistance to high temperatures, weather and abrasion coupled with chemical stability and electrical insulation make it a popular and commonly-used rubber for varied applications.
 

It is manufactured in three different forms with varying viscosity and curing temperatures:


  • Liquid Silicone Rubber (LSR) – As the name goes, this is in liquid form with good viscosity and flows well. It is a two-part silicone and the curing occurs only when the base material comes in contact with the catalyst. This is a thermosetting material and cannot be restored to its original form after curing. The range of hardness is wide, from 5 to 90 Shore A. The excellent liquidity ensures that the rubber can easily fill the most complex parts of the mold, making it perfect for automated injection molding, compression molding, transfer molding and other molds that have complicated designs or demand tolerance.
  • Room Temperature Vulcanizing Silicone Rubber (RTV) – This rubber is also in liquid state, but comes in both one-part and two-part formulations. The two-part variant is again of two types - condensation cure and addition cure. The former uses tin salts as a catalyst while the latter relies on a platinum-based catalyst to turn the liquid silicone into a solid form. It should be noted that these types of RTV silicone rubbers are not only quite different from each other, but also not even compatible with each other. However, all RTVs will cure at room temperature when they come into contact with air.

In general, RTVs cure to a soft or medium hard finish ranging from 15 to 40 Shore A. They have low shrinkage and can capture details well, making them suitable for injection molding, gravity casting and vacuum casting. They enjoy varied applications including mold making, casting, prototype-making, prosthetics and encapsulation. The tin-cured silicones have food safe, skin safe and transparent versions too.

High-Temperature Vulcanizing Silicone Rubber (HTV) – This is also known as Solid, Milliable or High Consistency Silicone Rubber. It is usually in the form of solid, gummy rubber blocks which are partly vulcanized, though liquid forms are also formulated. It goes without saying that the rubber has to be heat-cured at high temperatures to get the finished product. It is used for compression and resin-transfer. Silicone tubing and other shapes are often extruded from HTV silicone rubber.

EnvironMolds offers a great selection of high quality RTV silicone mold rubbers that can be used to make a silicone mold or cast. This popular art supplier also provides skin-safe, food-safe and translucent silicone rubber formulations. Apart from this, other related materials, supplies, tools and equipment are also available.

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