When it comes to clay modeling followed by casting, polyester and polyurethane resins are the most commonly used casting materials of choice by artists.
Both these resins cure creating a very hard cast.
They also can oftenyield the clearness of glass with a high gloss finish after proper sanding and buffing.
Then how does one decide when to use polyester resin and when polyurethane resins are better? For this, first let us take a look at the differences between these two popular resins.
Polyester resin is by far the less expensive of all resins available in the market.
It is a 2-part resin and that requires the addition of a catalyst (and accelerators too, at times).
The only drawback is that polyester resins have a very toxic odor and requires the artist to compulsorily wear a protective respirator mask.
Proper ventilation in the studio is also essential.
It also needs to be reinforced with a filler like fiberglass.
Over time cured polyester resin will develop spider web like cracks.
While polyester resin cures to a crystal clear finish, it tends to get yellow with age due to the exposure to UV light.
The pot time is also relatively short - just 8 to 10 minutes - and requires speedy work.
Users also complain of a high and unpredictable shrinkage rate, which makes polyester resins difficult to handle.
It is commonly used to bond fiberglass fabrics into hard sheets.
Polyurethane resins are more expensive but prove to be the most versatile of all resins.
They enjoy widespread usage in everything from rubbers and plastics to inks, medicines and much more.
Polyurethane resins bring various benefits like high durability and resistance to chemicals, oils, grease as well as abrasion.
They are relatively safe to use and do not emit any carcinogenic odors either.
Numerous varieties of low viscous polyurethane resins are available in the market with a choice of both opaque and water clear resins.
The casts will be highly detailed and do not tear easily either.
It is even possible to manipulate this resin to yield anything from a soft pliable rubber to a very hard and rigid plastic.
However, being prone to bubbles, appropriate treatment in a pressure pot or vacuum chamber is essential.
Coloring polyurethane resin casts also requires special colorants suited to the resin, which means that choice of colors can be limited.
The only known problem with polyurethane resin is that it is moisture sensitive and requires a dry climate for proper curing.
In humid environments, you will need to use a dehumidifier in your studio.
But the upside is that most polyurethanes cure very quickly (some as fast as within 5 to 10 minutes).
It follows that you have to work swiftly when mixing and pouring a polyurethane resin.
Therefore, polyurethane resin is always preferred for general mold making and casting works from clay modeling or other objects, while its polyester counterpart is primarily used for fiberglass fabrications.
Both these resins cure creating a very hard cast.
They also can oftenyield the clearness of glass with a high gloss finish after proper sanding and buffing.
Then how does one decide when to use polyester resin and when polyurethane resins are better? For this, first let us take a look at the differences between these two popular resins.
Polyester resin is by far the less expensive of all resins available in the market.
It is a 2-part resin and that requires the addition of a catalyst (and accelerators too, at times).
The only drawback is that polyester resins have a very toxic odor and requires the artist to compulsorily wear a protective respirator mask.
Proper ventilation in the studio is also essential.
It also needs to be reinforced with a filler like fiberglass.
Over time cured polyester resin will develop spider web like cracks.
While polyester resin cures to a crystal clear finish, it tends to get yellow with age due to the exposure to UV light.
The pot time is also relatively short - just 8 to 10 minutes - and requires speedy work.
Users also complain of a high and unpredictable shrinkage rate, which makes polyester resins difficult to handle.
It is commonly used to bond fiberglass fabrics into hard sheets.
Polyurethane resins are more expensive but prove to be the most versatile of all resins.
They enjoy widespread usage in everything from rubbers and plastics to inks, medicines and much more.
Polyurethane resins bring various benefits like high durability and resistance to chemicals, oils, grease as well as abrasion.
They are relatively safe to use and do not emit any carcinogenic odors either.
Numerous varieties of low viscous polyurethane resins are available in the market with a choice of both opaque and water clear resins.
The casts will be highly detailed and do not tear easily either.
It is even possible to manipulate this resin to yield anything from a soft pliable rubber to a very hard and rigid plastic.
However, being prone to bubbles, appropriate treatment in a pressure pot or vacuum chamber is essential.
Coloring polyurethane resin casts also requires special colorants suited to the resin, which means that choice of colors can be limited.
The only known problem with polyurethane resin is that it is moisture sensitive and requires a dry climate for proper curing.
In humid environments, you will need to use a dehumidifier in your studio.
But the upside is that most polyurethanes cure very quickly (some as fast as within 5 to 10 minutes).
It follows that you have to work swiftly when mixing and pouring a polyurethane resin.
Therefore, polyurethane resin is always preferred for general mold making and casting works from clay modeling or other objects, while its polyester counterpart is primarily used for fiberglass fabrications.
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