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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Embarking on the Journey of Life Casting

Posted by EnvironMolds , Labels: , , , , , Monday, May 31, 2021 7:12 AM

Life casting is not easy, but it is not rocket science either. Knowledge of the materials, the process and the application is essential, but you will not get the hang unless go ahead and give it a stab.

Life casting is a wonderful art that has captured the imagination of many an artist. While experienced and accomplished artists seem to easily create spellbinding life casts without breaking a sweat, fact of the matter is that making body molds and life casts is quite a complicated and painstaking process. It calls for working with care and precision while paying attention to minute details. Knowledge of the various materials, their properties and other factors is also essential. And the artist has to be particularly alert as he/she will be working on live models and cannot afford to harm/trouble them in any manner.
 

However, this does not mean that novices cannot try their hand at life casting! Following is what a beginner needs to know/do:


  • Different materials and supplies are required for making the body mold and life cast. Alginate is a natural material and can be safely used on the model; skin-safe silicone rubber is also a good option. A release agent has to be applied first and the mold has to be reinforced with a shell mold of plaster bandages.
  • You have to acquire the know-how about the various processes like how to properly mix the mold making material, apply it on the model, demold the body mold, pour the casting material, finish the life cast and so on. This can be learnt from instruction guides, tutorials or attending live workshops. Small tips and tricks from expert artists – like making the face mold with the model lying down, using soft water for mixing alginate and twitching the body to remove the mold - can make a world of difference.
  • Prepping the model is a crucial step of the life casting process. The model has to be informed about what lies in store, how to hold the pose, warning signs and so on.
  • You will never feel you are completely ready, so just go ahead and jump in. Do not be afraid to get your feet wet as theoretical information can only go so far. And there will definitely be loads of mistakes on the way. Try and try and you will definitely succeed very soon. In fact, both experience and perfection comes from trying.
  • Life casting is a messy job. Be prepared to get your hands dirty. Once you get the hang of the process, you will start enjoying it and even become proficient at it very soon.

In general, there are different materials and varied techniques for mold making and casting. Body casting and life casting follow most of the same principles, but it gets complicated by the fact that you are working on a real person and not an inanimate object. This is why many artists prefer to start with regular mold making/casting and then move to life casting!

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The Ins and Outs of Plaster Bandages

Posted by EnvironMolds , Labels: , , , , , Monday, May 17, 2021 5:59 AM

 Plaster of Paris is a common material that finds usage in construction sites, orthopedic chambers and art studios. When plaster is infused into gauze, it forms the very resourceful plaster bandages.


Plaster of Paris is a quick-setting gypsum plaster that comes in the form of a fine white powder. It forms a paste when mixed with water and when allowed to dry, it will take a solid form. The name plaster of Paris comes from the abundant gypsum found near Paris that is used for the preparation.

This is commonly used as a building material to form a protective coating on walls and ceilings apart from giving aesthetic finishing touches. The same plaster powder can be used to immobilize joint or limb fractures. In the medical field, it is applied as a slab, splint or full cylindrical cast on broken bones by orthopaedics. It dries to form a rigid cast that will hold the broken pieces of the bones in place and help them to heal. Dentists also often use plaster to make molds of the teeth to be replaced.

But not many people may be aware that woven fiber material (like gauze) can be soaked in a plaster solution and then dried to produce Plaster of Paris bandages.




Usage


Plaster bandages are usually used to form shell molds over flexible molds – like those made of alginate or silicone rubber. It forms a stiff covering that helps the mold retain its shape and the firm mold can then be used for casting purposes.

Apart from this, the bandages are also directly applied on both living and non-living models to make form molds. This will capture the basic shape without the finer details. Therefore, it is usually used for making belly molds (like pregnancy casting) and other basic shaped figures.

How to use?


Plaster bandages are fast and practical to use. The reverse process comes into play here – just soak the bandages in water and the moistened bandage will be ready to use. The bandages will harden rapidly, to form a resistant structure which does not lose shape.

Roll out the bandage and cut into the required lengths. Take a bowl of water and soak each bandage for a couple of seconds before squeezing it gently. Then apply on the required surface. Smooth it out with the fingers while ensuring that air bubbles do not get trapped inside.

Where to find?


EnvironMolds offers a complete array of materials, supplies and tools for making molds, casts and life casts. This includes top quality plaster bandages at very reasonable prices. The bandages are skin friendly and smooth. They offer rapid plaster immobilization with quick water absorption that enables faster application on the molds or even the body. There is appreciable mold ability which allows it to conform properly to where it is applied, thus facilitating easy and accurate molding.

What’s more, the same bandages can also be used in the medical arena to form plaster for bone and joint fractures.

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Tips for Working with Materials

Posted by EnvironMolds , Labels: , , , , , , , , Tuesday, April 27, 2021 1:56 AM

Mold making and casting is an easy job as long as you abide by the rules and instructions. Following are some useful tips that every artist should follow, irrespective of the type of mold or cast.

The world of mold making and casting opens up a veritable treasure trove of materials – each with their own specific characteristics, methods and usage. The commonly used options are clay, wax, alginate, moulage, plaster, gypsum, concrete, polyurethanes, rubbers, etc. Artists can try their hand at different materials and play around with different options depending on the type of mold or cast they are making.
 


Following are some general tips that beginners should keep in mind when working with almost any kind of material for making molds or casts:

  • Every packaged material comes with its own set of product literature like TDS (Technical Data Sheet), safety data sheet. Always read the label and other product information carefully before using the said product.
  • Work with materials that are already at room temperature and ensure that the room is at room temperature as well.
  • Stick to the prescribed methods and techniques – like mix ratio, type of release agents, compatible materials – at all times. At times, there may be other simple provisions that can make a world of difference. For instance, alginate requires the use of soft/bottled water; using hard water even unintentionally will render the material into a lumpy mess. It takes experience to deviate from the given methods to tinker with the viscosity or other features.
  • Some materials are suitable for certain applications and other options may not work as well, depending on the model, mold-making/casting material and other factors. Choose an appropriate material for the task. Seek advice from experts if needed.
  • Always shake or stir components thoroughly before use. Sludge can sit at the bottom of the box while oil tends to float on the top. Shaking before use followed by proper mixing of the components together is crucial.
  • Always mix a small amount as a batch test at first. It is better to get a feel for the material before mixing in large quantities for the project as it can end up as a time-consuming and expensive mistake.
  • First try your hand at making a small mold or casting, use a small object as a test model before moving on to larger molds or castings.
  • Keep the pot time and working time in mind. Avoid pouring delays as this will add to the working time and can affect the quality of the mold or cast.
  • Before pouring, check if the sealer and release agent have been used, if required. Also check the mold/mold box for leakage before pouring the material.
  • Wear gloves when working with any materials. Some materials may require the use of mouth mask, safety goggles and other additional protection.
  • Use clean and good tools for any project. Assemble the required tools and supplies before starting the work.
  • Follow the indicated set time and demold time to the T. Else, the mold or cast will end up distorted/deformed and unusable.
  • Do not hesitate to ask any questions to the experts about the clay mold, resin casting, cold casting, alginate life casting, etc.

All the best for your new project!

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Silicone Rubber - Different Faces and Usage

Posted by EnvironMolds , Labels: , , , , Tuesday, April 13, 2021 6:38 AM

Silicone rubber is a versatile material that is used for different purposes in both the art and manufacturing world. It displays many useful properties and comes in a few different types too.

Silicone rubber is a popular compound that enjoys widespread patronage across industries and applications. It is commonly used for bonding, sealing, potting, encapsulation, coating, mold making and casting works.

The main benefit is that silicone rubber molds that can be used for manufacturing different types of technical and mechanical parts for industry and medical devices. Apart from molds, silicone rubber is also used as a release agent, adhesive or the base material for the cast. It also functions well in the potting of electronic components in high-tech industrial and scientific equipment.

Artists normally use the rubber to make molds for toys, candles, soaps, food and baking containers apart from special effects. There is a special variety of silicone rubber that is safe for the skin and is used to make body molds.

The same rubber can be used to make casts too and is the material of choice for mask making and doll reborning.


Getting to know Silicone Rubber


RTV silicone rubber is commonly used for molding and casting projects. It delivers various useful properties like ease of use, flexible, tough, durable and tear resistant. This versatile material can reproduce almost anything without damaging the surface of the model. What’s more, the excellent mechanical properties and low surface tension enable it to replicate the mold without losing any of intricacies of the original - the minutest of details will be captured in the mold even down to the skin pores and fingerprints. It can even be cast in abrasive materials.

Silicone rubber formulas are remarkably stable in a wide temperature range and prove to be non-flammable and non-combustible. There is a good level of thermal conductivity too.

The room temperature vulcanizing rubber comes as a 2-part formula – one is the liquid base and the other is the catalyst. They have to be mixed in the specified proportion which can vary from formula to formula. The catalyst will react with the base to deliver the intended properties. It can even be customized to produce the required degree of viscosity and adherence along with varying mechanical, chemical or temperature resistance characteristics.

The rubber comes in two different types – addition cure and condensation cure. The primary difference is in the catalyst - Addition cure silicones use a platinum-based catalyst (usually 10%) while condensation cure silicones need a tin-based catalyst (usually 5%). They have different characteristics and usage and most importantly, are not compatible with each other.

EnvironMolds offers a broad range of materials, supplies, tools and equipment that include both silicone mold and casting rubbers. There are different formulae options to suit varying needs and preferences, like MoldRite 25 Silicone - Classic Mold Making Silicone, BluMold RTV Silicone, 5-Minute Mold Putty for Faster Mold Making, Food Safe Silicone -- BakeSil FDA Approved, LifeRite Skin Safe Silicone for Life Casting and SkinRite 10 Translucent Special F/X Silicone.

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The Ins and Outs of Latex Rubber

Posted by EnvironMolds , Labels: , , , , , Wednesday, March 31, 2021 4:29 AM

Latex rubber is an artist’s weapon that can be wielded in varying manners. The properties and versatility of liquid latex rubber are to be experienced to be believed. Let’s find out more about this….

Liquid latex rubber is a versatile product that lends itself well to varied applications. The wonderful part about the rubber is that it is suitable for making both molds and casts. Changing the viscosity will change the application – latex molds require more thick and viscous formulations than casts. The degree of flexibility of the latex can be further controlled by adding an appropriate filler during the casting process.


Latex mold rubber is commonly used for mold making as it is economical, durable and easy to use. The molds will be tough, tear resistant and can be reused multiple times. They are used to cast plaster, polyester resin, urethane and even abrasive materials like concrete.

On the other hand, the casting variant of latex rubber is used for making hollow molded rubber articles like toys, balls, props and even display articles. It enjoys great patronage for making masks, puppet heads and even special effects like wrinkles, scars and gashes for theatrical work.

Latex rubber can be brushed, sprayed, poured or dipped for making the molds and casts. Brushing requires successive coats and sufficient time should be allowed for drying between each coat. This process is continued till the desired thickness is obtained. Spraying will also involve a similar process.

Latex is usually cast in plaster molds because of the porous nature of plaster. When the rubber is poured into the mold, the plaster sucks the water out and leaves a thin latex skin behind. Slip latex casting is a commonly preferred method as it is comparatively easy and does not leave any brush marks either.

When it comes to demolding the latex mold or cast, an easy trick is to dust the latex with talcum powder before peeling it off slowly. The powder will keep the fresh latex from sticking to itself. The latex mold will need to be supported before casting so that the flexible rubber can retain its shape.

Latex rubber is also used to form a protective coat on different items. The latex coat can make fabrics waterproof. It can also form a protective covering on tools that will provide a sound and comfortable grip even while insulating them against electrical hazards.

The most common use of latex rubber is for making a latex mask. This can be used for special effects in movies or even a fun element for Halloween and other occasions. It is usually cast in a face mold made of plaster bandages and then the desired characteristics are built on it step by step.

Other tips to keep in mind when working with latex rubber is that it contains a good amount of alcohol. Proper ventilation is required and do not inhale it too deeply or frequently. Similarly, the rubber will become unusable if frozen. Store it carefully in the winter months of the year.

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