Functional and design requirements for controlling optical hazards with semi transparent curtains were developed. Characteristics of open arc welding and adverse health effects from intense optical radiation were analyzed. Design objectives for the curtain were to filter out hazardous ultraviolet (UV) radiation and blue light, to provide sufficient transparency to allow for adequate viewing, and to increase ambient illumination of the general area. These objectives suggested a curtain that could absorb UV radiation and blue light, transmit some visible light, and reduce disabling and discomfort glare. The minimum attenuation factor needed for the curtain was determined to be 100,000 microWatts (microW). Incorporating a 10 fold safety factor gave a transmission goal of 1,000,000microW. Limiting blue light was achieved by adding UV absorbed dyes to the curtain. A class of commercial dyes was considered suitable. Although the dyes offered little absorption of infrared, this was not a concern because the bands were not harmful. The glare of the arc was decreased by controlled diffusion in the welding curtain. A specialized method used minute refracting elements which resulted in a reduction of luminance for small features but left the large features of the area unchanged. The ambient illumination was increased by the addition of fluorescent dye whose emission transmitted through the curtain provided more luminance. The authors conclude that transparent welding curtains can prevent the hazard of UV radiation or infrared radiation accompanying the welding process.