Recently, a new caster asked me if there were negative affects to not wearing a respirator while using urethan resin. Another new caster told me that he was using Smooth-Cast 326 but didn&#;t know what kind of resin it was, so I decided to post this discussion. I myself are pretty new to resin casting, so I&#;m writing this to open the discussion. Please correct me if you know any of this information to be inaccurate or misleading. Thanks.Many of us casting artisans out of resin are using urethane resin. I&#;m sure some people are using other stuff, but I&#;m addressing urethanes. The way I understand it, the term urethane (when talking about resin) is just short for polyurethane resin. (There is such thing as urethane compounds, but it is something quite different, which adds to the confusion.) For instance, Smooth-Cast 326 is a common resin used amongst our community. Smooth-On has it listed under Urethane Resins. However, when you look at the product Safety Sheet (which is located on their website: https://www.smooth-on.com/msds/files/Smooth-Cast_326_327.pdf ) you will notice that the General Use description for both part A and B are "Polyurethane Elastomer.&#;Now, if you call Smooth-On and talk to a technician, such I have 3 times, they will tell you not to inhale the vapors that come off of a catalyzing mixture. I had one of their employees tell me that I just &#;shouldn&#;t huff the vapors.&#; Another employee told me that it&#;s &#;really not that bad.&#; While another employee told me that &#;all resin is dangerous&#; and I should &#;take the necessary precautions to protect myself from inhalation of vapors.&#; The web page, along with most of the employees have told me that it is alright to use the product in doors, but it needs to be a used in a well-ventilated area. Others have suggested that a &#;room-sized&#; ventilated area is fine. I&#;ve been warned not to do it in my closet or small bathroom. (Ok. Thanks.)Now, I found this one article online at http://blog.thegreenguide.com/the-truth-about-polyurethane/ which I admit is kind of a random blog, (but wikipedia confirms some of this information about polyurethanes isocyanates (an organic/carbon compound) being dangerous to one&#;s health. ( https://en.wikipedia.org/wiki/Polyurethane#Health_and_safety ). The effects of inhalation listed in this article include lung irritation, asthma attacks, difficulty breathing, causing lung infections, and brain swelling (in a bad way.) Also prolonged exposure for workers can health disorders such as unsettled stomach, vomiting, and dizziness.So what&#;s the truth about polyurethane resin? Well, it&#;s dangerous. Just read the rest of the Safety Sheet again ( https://www.smooth-on.com/msds/files/Smooth-Cast_326_327.pdf .) Notice the repeated warnings about Part A: &#;Harmful if inhaled;&#; &#;May cause allergy or asthma symptoms or breathing difficulties if inhaled;&#; &#;May cause respiratory irritation;&#; &#;May cause damage to organs (Olfactory organs)) through prolonged or repeated exposure (inhalation).&#; Part B: &#;Fatal if inhaled;&#; (which sounds bad).In conclusion, I&#;m not trying to be overly dramatic. I&#;m just worried that their are young people out there that read all of this communities&#; posts and get really excited to get involved, but never stop to consider what it is they are getting involved in. I mean it is a ton of information and none of it is straightforward, so I'm just trying to help some find the relevant information. The thing is driving a car is dangerous, but when you put on your seatbelt, only drive when well rested, follow traffic laws, etc. you reduce the risk of being in a fatal accident. Anything can still happen, but what kind of life is it if you just sit around in your house and never take any risks. If you&#;re reading this you are probably passionate about resin casting, so I wouldn&#;t ever try to stop you from pursuing that. (I don&#;t plan to stop either.) However, just take the necessary precautions to protect yourself, such as wearing a respirator (note that only respirators that protect from ORGANIC VAPORS will do you any good), using a fan to waft vapors out of your face, and use in a well-ventilated area. It&#;s really not that big of a deal. Take care of yourself, so you don&#;t die before we see your cool caps. Cheers.
There are several factors that should be considered when selecting a casting material (e.g., desired weight, appearance, durability, texture, cost, timing). One of these factors is the casting method. Popular methods include:
[If a mold also needs to be made, it is important to select the casting method beforehand so the mold can be constructed appropriately. A mold used for rotational casting may be designed differently than a mold made for solid pour castings.]
There are advantages and disadvantages to each casting method and certain materials can work more efficiently for one method over another:
Casting MethodsMethod Defined
Advantages
Disadvantages
End Uses
Recommended Polytek® Product(s) for Method*
Solid Pour
Material is poured into the mold, resulting in a solid casting.
Fast
Strong
Heavy
Potential high cost
Small objects
Industrial tools
All Casting Materials (View Casting Plastics, Foams & Epoxies, View Casting Rubbers)
*Epoxy Resins should not be used for large castings &#; it can be dangerous.
Gel Coat and Layup
A thin surface coat is applied and then subsequent layers of reinforcing materials (e.g., fiberglass mat and resin) are built-up to a thin, strong laminate.
Lightweight
Uses less material
Time-consuming
Rigid molds
Mold shells
Large Objects
Props and displays
Bonded bronzes
Poly 15 Series with thickening agent (e.g., PolyFiber II)
Slush Cast
Casting material is manually rotated in the mold, creating a thin layer, which results in a hollow, lightweight casting.
Lightweight
Uses less material
Time-consuming
Props and displays
Art objects
Bonded bronzes
EasyFlo 60 or EasyFlo 120
Rotational Cast
A closed mold is rotated by machine as a small amount of casting material coats the surface and sets, which results in a hollow, lightweight casting.
Link to zen
Fast
Easy
Lightweight
Six-sided parts
Requires a rotational casting machine
Large statues
Props and displays
Hollow parts
EasyFlo 120
Injection
Liquid is forced into the mold under pressure.
High quality parts
Requires setup time
Requires a machine or pressure pot
Thin-walled parts
All Casting Materials (View Casting Plastics, Foams & Epoxies, View Casting Rubbers)
*Epoxy Resins should not be used for large castings &#; it can be dangerous.
Solid Pour with Vacuum/Pressure
Material is poured into the mold and then vacuum or pressure is applied, which eliminates bubbles in the resulting casting.
High quality parts
Requires setup time
Requires a vacuum pump or pressure pot and chamber
Prototypes
Figurines
Clear castings
All Casting Materials except PolyFoam
*Epoxy Resins should not be used for large castings &#; it can be dangerous.
Direct Layup/Spray (No Mold)
Material is sprayed over a screen armature or foam substrate. Surface detail is sculpted into the wet casting material or cured plastic hard coat.
Lightweight
Uses less material
Time consuming
Often requires equipment
Produce single part
Amusement/themeparks
Sculpted rocks
Props and displays
EasyFlo Spray FR
*The recommended products listed above are provided as general advice. Material requirements vary from project to project; please contact us to discuss the right choice for your particular application.
If you want to learn more, please visit our website resin sand casting services.