Difference Between Fiberglass and Plaster Casts for Broken Bones:


When a bone is broken, it needs to be supported so that it can heal properly, Orthopedic specialists Fiberglass and Plaster Casts for the leguse casts to protect and support the broken bones. A cast refers to a supportive bandage that is wrapped around the injured spot and the surrounding areas. Casts are available in different sizes and shapes, but the commonest types of cast materials are fiberglass and plaster. Although casts can be uncomfortable, they are effective and efficient in treating broken bones.

Both fiberglass and plaster casts are applied to fractured limbs to immobilize them and allow the injury to heal. They are also used after surgeries, including correction of clubfoot and other limb deformities. Although fiberglass is the material of choice in the U.S., plaster casts are still used to immobilize fractured bones.

If your child has a fractured bone, you can choose from different types of casts depending on your age and the type of fracture sustained. Your child may need to use a cast for about 4 to 10 weeks to help the injury heal. Your doctor will choose the type of cast that is most suitable for your child’s injury.


Fiberglass casts are used when the bone is in position, or if the healing process has started. They have lighter weight and can work for a longer period. They are also more breathable than plaster casts. Due to their sturdy nature, they require less maintenance. Most of the casts used today are fiberglass.

A few layers of cotton are wrapped beneath fiberglass and plaster casts to protect the skin. The cotton must be clean and dry to enhance comfort.


Fiberglass casts have lots of advantages (for both doctors and patients). Some of the advantages include the following:

  • Fiberglass casts are more porous than plaster casts. This allows the doctor to take X-rays of the injury without removing the cast.
  • Since they are porous, they are also more breathable, thereby making them more comfortable to wear.
  • They make the skin less prone to irritation.


  • Although fiberglass casts are more waterproof than plaster casts, they are not fully waterproof. The soft padding underneath the cast is not waterproof but the outer layer is. In some cases, the doctor may make the entire casting waterproof by putting a waterproof material under the cast.
  • The process of making the entire cast waterproof costs more money and also consumes more time. You may need to discuss this with your doctor to find out if a waterproof cast will suit your child’s lifestyle.


Although fiberglass material is newer, most casts are still made from plaster. A plaster cast is used for repositioning the fractured bone. The cast is used for this purpose because it can be well molded, thereby offering more precise support to the bone.

The issue patients may have with plaster is its heavy weight. A plaster cast is a burden for the patient because of the heavy material that is used in making it. The shape of a plaster cast can also be distorted by water thereby inhibiting the healing process.


  • They are less expensive.
  • Plaster casts are easier to mold around some areas.


  • They require more care than fiberglass casts. They must not get wet because this can crack or disintegrate the plaster. Parents will need to wrap the plaster in several layers of plastic if you want to bathe your child.
  • Plasters take several days to fully harden.
  • They are heavier and this can be challenging for small children.

Major Differences Between Fiberglass and Plaster Casts


Fiberglass cast is made from woven fiberglass which is coated with polyurethane resin. A plaster cast is made from naturally occurring gypsum (referred to as plaster of Paris) that is used for coating fiber bandages.


Fiberglass cast has a webbed texture and appearance and it is usually colored. Some of its common colors include pink, blue, and green. A plaster cast has a smooth texture and it is always white.

Weight, strength, and durability

Fiberglass casts have a lighter weight and are also stronger than plaster casts. Since they are more resistant to water damage and wear, they last longer than plaster casts. However, none of them is waterproof unless a particular waterproof liner is used with a fiberglass cast.

Porosity and drying time

Unlike a plaster cast, a fiberglass cast is more porous and this makes it more comfortable to wear. Also, fiberglass can dry within 30 minutes to two hours while it takes a plaster cast about 48 hours to dry. Cast care is very important.

However, it is easier to mold plaster cast than fiberglass cast.


A fiberglass cast is more expensive than a plaster cast. The cost of a fiberglass cast may not be covered by some insurance plans.


Fractured bones take many weeks to many months to fully heal. The pain usually stops even before the bone becomes solid enough to withstand the stress of daily activities. It is necessary to wear the cast until the fractured bone is fully healed and capable of supporting itself.

Your child may lose some muscle strength in the injured area while wearing the cast. This is why it is important to do some exercises while his or her bone is healing and after the casts are removed. Exercise will help in restoring muscle strength, flexibility, and joint motion.

Frequently Asked Questions About Fiberglass and Plaster Casts

What should I avoid while wearing a cast?

Fiberglass and plaster casts that are used with conventional padding are not waterproof. Ensure your child’s casts are dry while bathing or showering by covering the cast with two layers of plastic that is sealed with duct tape or a rubber band. Your child should not swim if he or she is not wearing a cast that is waterproof.

Can I walk in a fiberglass cast?

Fiberglass casts dry quickly. As a result, they get hard within a short period to protect the injured limb. When your child feels comfortable, he or she can put weight on their foot or leg.  Your child can prop up the injured limb on a pillow whenever they sit or lie down within the first 3 days of applying the fiberglass cast.

The differences between Fiberglass and Plaster casts

A fiberglass cast is better than a plaster cast in many ways. Fiberglass has less weight thereby making the cast made from it lighter. Fiberglass casts are also more porous and durable. They give room for air to flow in and out.

Fiberglass casts are the preferred options for limbs that need to be X-rayed while healing.

Can my child use a waterproof cast?

This is a good question that you should ask the doctor during your appointment. A waterproof cast may be suitable and may not be suitable for your child. If your child needs to get a waterproof cast, then he or she needs to wait for at least one to two weeks because the tissues that surround the fractured bone usually swell first.

Most insurance companies do not cover the cost of a waterproof cast. If that is the case, you will need to buy a special waterproof material to protect the child’s cast.

Waterproof casts are suitable for swimming pools, showers, and baths. Ensure that your child does not wear the waterproof cast in a hot tub, a pond, the ocean, or in a hot tub. Sand should also be prevented from having access into the cast as this can cause skin irritation.

At Medical City Children’s Orthopedic and Spine Specialists, we provide waterproof casts for kids that are at least 18 years old.

To maintain the lining of the cast, waterproof casts need to be submerged in water every day. When it’s time to remove your child’s cast, ensure you get in touch with an experienced technician or clinician.

How is a cast removed?

The doctor will use a special cast saw with a vibrating blade (one that does not spin). The saw will cut through the outer layer of the cast (without touching the lining).

Don’t remove the cast yourself. You may seriously injure your child’s skin, blood vessels, and fractured limb if you use a home saw or other cutting materials.

Get An Expert Diagnosis, Treatment, and Rehabilitation for Bone, Joint, or Connective Tissue Disorders

If your child needs to immobilize a fractured limb, your doctor may choose to use a plaster or fiberglass cast. You need to discuss your lifestyle with your doctor so that they can choose the ideal casting material that is suitable for your needs.

If appropriate, request a fully waterproof fiberglass cast. Although it may be more expensive and may need more time to be applied, it’s worth it because you can use it to bathe and shower your child.

Here at Medical City Children’s Orthopedic and Spine Specialists with offices in Dallas, Arlington, Frisco, and McKinney, Texas offer soft fiberglass casts. All our 4 locations in the Dallas metroplex) are a one-stop destination for X-ray and fracture care. Emergency rooms refer patients to us as we are skilled in healing children with broken bones.  If your child is in pain from a broken bone, get in touch with us today at 214-556-0590 to get the best orthopedic care.


Healthline: Types of casts for broken bones