What is the Fiberglass Pultrusion Process?Pultrusion is a process where raw materials (in this case glass fiber reinforcements and resins) are drawn into a profile die by a mechanical pulling force. These fibers are injected with resins while under tension where they are combined and cured. This technology is used to create an entirely pultruded door panel. A high-density, closed cell polyurethane foam core accompanies the woven rovings, woven knits, veil and resins into the die. This core reduces the weight of the door without diminishing its strength and delivers outstanding thermal performance. Multiple layers of glass fiber reinforcing fabrics envelop both sides of the core panel as it moves through the process: a woven layer for impact resistance, two layers of random continuous filament for flexural strength, and a thin veil top layer to provide a smooth surface finish. Glass reinforcements wrap around the panel edges from both sides to improve the door’s structural properties. This combination of reinforcing fabrics is necessary to consider, as it is this high fiber-to-resin ratio that gives the fiberglass door such impressive strength. An FDA- and USDA-compliant resin fully saturates the glass fiber fabrics before the door enters the profile die. Here, the die compresses reinforcements around the core panel. The resin fully cures around the core as the panel passes through the heated portion of the die. This process produces a hermetically sealed, incredibly durable door panel free of voids. The FRP has as much as a 65% glass content and provides excellent impact resistance and screw holding strength.
Performance Beyond Avoiding Rust and Rot of Metal and Wood DoorsWhile fiberglass doors have gained favor in both the commercial and residential markets, it is important to point out key opportunities for improved performance that a fiberglass pultruded door delivers. The benefits go far beyond the avoidance of rust, rot, and the replacement cost of using wood and steel doors.
Constructed with Materials that LastThere is no door built to last like a fiberglass door. Fiberglass boasts impressive strength to weight ratio. Lighter weight allows the hardware attached to have a longer life. All fiberglass doors, so long as they are sealed, are impervious to moisture, chemicals, seawater and salt solutions. A fiberglass pultruded door delivers extraordinary performance.
No molds – No Gel CoatThe pultrusion process works without the use of a mold and therefore does not require the use of a gel coat. A fiberglass pultruded door is prime coated and finished with a two-part urethane finish that delivers superior UV protection. This 5 mil thickness finish is resistant to corrosive airborne agents and is not susceptible to chalking, discoloration, or leaching. The color maintains a high gloss appearance and flexibility for many years, even in full sun exposure and corrosive environments. This aliphatic polyurethane coating allows for easy surface damage repair. Pultruded doors with this finish are FDA and USDA compliant.
Hermetically Sealed – ReallyA manufacturer can feed various core materials into the die. There is a bias toward the use of a closed cell polyurethane foam core to enhance its structural performance. This process allows doors, in constant contact with water or high humidity, to avoid constant expansion and contraction. Continual expansion and contraction quickly deteriorates a metal or wood door and damages the physical properties of a fiberglass door. Since pultruded doors are hermetically sealed, they avoid this damaging expansion and contraction.
Above and BeyondFinally, pultruded fiberglass doors can use alternate cores adding scalable protection performance. You can order these doors manufactured with fire or ballistic cores adding safety performance to entry ways where needed. You even can order oversized doors pultruded in very long lengths without any seams! Click below to read the original article by Special-Lite VP of Sales and Marketing, Roger Stempky, as published in DHI’s November 2016 Doors + Hardware Magazine:
If you love one or all of our Special-Lite fiberglass doors, did you know we have a harmonizing fire-rated model available too?
Special-Lite is the manufacturing leader for fiberglass doors. In 35+ years, we migrated from the first and best fiberglass school door into many markets and industries – all having unique door needs. One of those needs is a fire-rated fiberglass door to use in rated entrance locations to match our door products. We solved this need through engineering and by challenging our expert craftspeople to manufacture fire-rated fiberglass doors and frames. They are perfect for new construction or retrofit projects.
We offer two fire-rated fiberglass door types: FRP/Stainless Steel & Fiberglass
What? Yes, both construction types use FRP face sheets, but the construction method and design are different. It is important that you understand the unique construction methods so you can select the type best suited to your location.
FRP/Stainless Steel Fire-Rated Door
Special-Lite builds FRP/Stainless Steel fire-rated doors using a fire-resistant mineral core in 30, 45, 60, and 90-minute rated versions. We chemically bond FRP face sheets to this mineral core. We screw-apply the stainless edges, then weld and buff the corners. Stainless steel vision lite kits are also an available option!
Our fiberglass fire doors are hand measured throughout the entire process to ensure we meet specifications. Custom-built punches used by skilled craftspeople deliver precision edge preps on the stainless steel edge pieces. These punches prep for hardware such as mortise locks, strikes, and flush bolts.
Below you can see a graphic representation of the FRP/Stainless Steel fire-rated door’s construction. Fire-rated cores are ordered to fit specifications and are reinforced on the top, bottom, and hardware areas. The stainless steel door edge is durable and protects the door edge from damage involving gym bags, suitcases, hospital beds, and equipment.
Fiberglass Fire-Rated Door
Our other fiberglass fire-rated door construction does not utilize stainless steel door edges. We construct these doors with a fire-rated mineral core featuring edge blocking for superior screw hold performance. We again chemically bond FRP face sheets to the mineral cores. You can order these fiberglass fire-rated doors in many size variations, with fire ratings from 20 to 90 minutes.
In the drawing above notice the pultruded fiberglass fire-rated door frame! When you combine this pultruded fiberglass fire-rated framing with our fiberglass fire-rated door, you will enjoy a beautiful, complete and cohesive entry system!
Both the Fiberglass Fire-Rated Door and the FRP/Stainless Steel Fire-Rated Door construction uses our .120” thick fiberglass face sheets giving our customers many options:
- AMP Wood Grain (Fiberglass) Face Sheet We are very excited to offer you a faux wood grain fire-rated door, the Fire-Rated AMP-Clad SL-22! A wood grain look presents many design opportunities for a warm and home-like feel without sacrificing the durability of FRP. This door is perfect for hospitals, long-term care facilities, retirement residences, hotels, educational housing, places of worship, and traditional education buildings. If your design team has chosen to use our SL-19 flush or SL-18 colonial doors, the SL-22 is the fire door for you! Below is a photo featuring a hotel with this door!
- Pebble Grain SpecLite 3® FRP (Fiberglass Reinforced Polyester) Face Sheet Our most popular FRP face sheet is used on both the SL-21 and the FR-20P/45P/60P/90P fire doors. The pebble grain FRP face sheet, our proprietary SpecLite 3®, unlike competitors’ pebble grain FRP sheets has a mylar coating. This coating provides scratch and graffiti resistance, as well as making doors incredibly easy to clean. This face sheet is available in 12 standard thru-color options. This option is the perfect choice for any location experiencing hard use or abuse. Also, this is the same face sheet used on the SL-17 and the AF-217 non-fire-rated doors so our customers may coordinate as required.
- Sandstone Textured FRP (Fiberglass Reinforced Polyester) Face Sheet You’ll find the sandstone texture FRP face sheet on both the SL-23 and the FR-20S/45S/60S/90S fire doors. The sandstone textured FRP face sheet provides a smoother look than the pebble grain for applications such as schools, childcare centers, hospitals, and industrial buildings. This face sheet is available in all 9 standard thru-color options. Also, this is the same face sheet used on the SL-20 and AF-220 door non-fire-rated doors so our customers may coordinate as desired.
- Smooth FRP Face Sheet We use our smooth FRP face sheet on only one of our fire-rated doors – the FR-20/45/60/90. This option provides a beautiful, sleek, modern, and easily cleanable surface. Hermetically sealed with no cracks or crevices, these fire doors are impervious to moisture, chemicals, and bacteria. Standard color selections include 10 standard colors, and the option to use custom colors. All finishes are industrial two-part aliphatic polyurethane, which meets USDA qualifications for incidental food contact. These fire-rated doors are perfect for food prep areas, schools, fitness centers, and pharmaceutical applications. We also think you could get creative with the modern look and color selection and use this durable door for a variety of industries or buildings. Gloss black in an upscale hotel, anyone? This smooth fiberglass fire-rated door works seamlessly with the AF-100 and AF-200!
Our fire-rated doors are compatible with a wide variety of hardware. Particularly relevant is the ability to have surface vertical rods less bottom rods on our FRP/Stainless Steel models, which is preferable by hospitals. Hardware compatibility for both fire-rated constructions is listed below: