News and Discussions > History & Trivia

Radiation control pratices

(1/2) > >>

Origin of the Trefoil

The three-bladed radiation warning symbol,  as we currently know it, was "doodled" out at the University of California Radiation Laboratory in Berkeley sometime in 1946 by a small group of people.  This event was described in a letter written in 1952 by Nels Garden, head of the Health Chemistry Group at the Radiation Laboratory:  "A number of people in the group took an interest in suggesting different motifs, and the one arousing the most interest was a design which was supposed to represent activity radiating from an atom."

The first  signs printed at Berkeley had a magenta (Martin Senour Roman Violet No. 2225) symbol on a blue background. In an earlier letter written in 1948, Garden explained why this particular shade of magenta color was selected: "it was distinctive and did not conflict with any color code that we were familiar with. Another factor in its favor was its cost. .  . The high cost will deter others from using this color promiscuously."  Explaining the blue background, he said, "The use of a blue background was selected because there is very little blue color used in most of the areas where radioactive work would be carried out."

Garden did not like yellow as a background: "the very fact that . . . the high visibility yellow stands out most prominently has led to extensive use of this color and it is very common." To compensate for the lower visibility of the blue, Garden even toyed with the idea of including diagonal white stripes across the sign.

Despite Garden's view to the contrary, most workers felt that a blue background was a poor choice.  Blue was not supposed to be used on warning signs, and  it faded, especially outdoors. The use of yellow was standardized at Oak Ridge National Lab in early 1948.  At that time, Bill Ray and George Warlick, both working for K.Z. Morgan, were given the task of coming up with a more suitable warning sign,  a blue background being too unacceptable.  Ray traveled to Berkeley and picked up a set of their signs. Back in Oak Ridge, Ray and Warlick had their graphics people cut out the magenta symbols and staple them on cards of different colors. Outdoors, and at a distance of 20 feet, a committee selected the magenta on yellow as the best combination.

All sorts of variations on the Berkeley design were suggested and implemented during the 1940s and early 1950s. Especially common were signs that incorporated straight or wavy arrows between, or inside, the propeller blades.  By the late 50s,  ANSI standards and federal regulations had codified the version of the warning sign used today.   Present regulations also permit the use of black as a substitute for magenta.   In fact,  black on yellow is the most common color combination outside of the U.S.

Link to full article

Rad Sponge:
I like to think it was foreshadowing the cometh of the Navy MM/ELT since it is almost identical to the Machinist Mate rating badge.

But your factual account is good too.

R/ Sponge

The following link is to a method of monitoring radon using your TV set (sort of, its really more of an observation). Its not a new concept it was published in the December 1986 HPS Newsletter.

Mike McFarlin:
Who would have thunk it?

marlin.... ya wooda thought that they cood have included security guards uniforms in the mid80s, back when polyester ruled!


[0] Message Index

[#] Next page

Go to full version