Casting Methods: Advantages & Disadvantages

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:

  • solid pour
  • gel coat and layup
  • slush casting
  • rotational casting
  • injection
  • solid pour with vacuum or pressure
  • direct layup/spray (without a mold)

 

[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 Methods

Method 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.

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.

 

Do you have a casting method or material question that you would like to ask a member of our technical support staff?

Call us at 800.858.5990.

Email us at sales@polytek.com.

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