Skip to main content
FR-4 (or FR4) is a NEMA grade designation for glass-reinforced epoxy laminate material. FR-4 is a composite material composed of woven fiberglass cloth with an epoxy resin binder that is flame resistant (self-extinguishing).

"FR" stands for "flame retardant", and does not denote that the material complies with the standard UL94V-0 unless testing is performed to UL 94, Vertical Flame testing in Section 8 at a compliant lab. The designation FR-4 was created by NEMA in 1968.

FR-4 glass epoxy is a popular and versatile high-pressure thermoset plastic laminate grade with good strength to weight ratios. With near zero water absorption, FR-4 is most commonly used as an electrical insulator possessing considerable mechanical strength. The material is known to retain its high mechanical values and electrical insulating qualities in both dry and humid conditions. These attributes, along with good fabrication characteristics, lend utility to this grade for a wide variety of electrical and mechanical applications.

Grade designations for glass epoxy laminates are: G-10, G-11, FR-4, FR-5 and FR-6. Of these, FR-4 is the grade most widely in use today. G-10, the predecessor to FR-4, lacks FR-4's self-extinguishing flammability characteristics. Hence, FR-4 has sincewhen? replaced G-10 in most applications.
Fenhar FR-4 epoxy resin systems typically employ bromine, a halogen, to facilitate flame-resistant properties in FR-4 glass epoxy laminates. Some applications where thermal destruction of the material is a desirable traitcitation needed will still use G-10 non flame resistant.
FR-4 by fenharxz.com August 7, 2024
FR-4 mug front
Get the FR-4 mug.
See more merch

The FR4WG 

The act of eating shit out of a dudes ass while fondling one dudes balls while beating the other dude off into a glass cup and the drinking the shit down his own throat with the cum.
its close to the sleepy white boy The FR4WG
The FR4WG by Zombie ranark July 3, 2010

gzhtb .7uüuzih6d fxcv<>‡ÙÅ∂‚fr4gt65

When pp go ouchie :,,,(
Oh no mah weewee

I‘M GONNA gzhtb .7uüuzih6d fxcv<>‡ÙÅ∂‚fr4gt65!

breatharian 

One whos diet consists of air, light, and prana, with a possible sip of water now and then.
The breatharian has air, light, and prana for food.
breatharian by leena gabor November 8, 2005
Word of the Day on June 3, 2026

A Booger In The Nose Of Progress 

Anything that impedes or otherwise interferes with a process going forward.
"Militarily, that inquest was a booger in the nose of progress."

or

"As far as human rights are concerned, this political infighting is a booger in the nose of progress."
Word of the Day on June 2, 2026

🤡🫵🏻

How to say "you're an idiot/clown" using only emojis.
Person 1: Insert completely incorrect and/or idiotic statement here
Person 2: 🤡🫵🏻
Word of the Day on June 1, 2026
Fogey/fogy /fougi/ sl. (early 18C+, orig. Scot) old-fashioned, stuck-in-the mud.
Person with old fashioned ideas which he is unwilling to change: Come to the disco and stop being such an old fogey!
You think me an old fogeyand an old tory, his thoughtful voice said. I saw three generations since O’Connel’s time. I remember the famine. Do you know that the orange lodges agitated for repeal of the union twenty years before O’Connel did or before the prelates of your communion denounced him as a demagogue? You fenians forget some things. (James Joyce, Ulysses. Penguin Books,1992. p. 38)
fogey by Petyush September 14, 2005
Word of the Day on May 31, 2026