According to History of Underclothes, the dress shirt protector was popular in Britain from about 1897 and consisted of “a pad of white quilted satin faced with white silk.”
North American newspaper archives reveal that in the United States it was more often referred to as a full dress protector and sometimes a dress shirt shield and debuted a decade earlier. Initially made of cotton and wool then of satin or silk it was essentially an oblong scarf broad enough to cover the expanse of shirt revealed by the open tailcoat front and low-cut evening waistcoat. It differed from the white silk dress scarf in couple of ways that made it more practical. Firstly, it was black owing to its purpose of shielding the snow-white expanse of shirt front from the soot that plagued coal-powered cities of the time.
Secondly, it was quilted to protect the wearer’s chest from the unhealthy effects of cold weather. Unlike all other types of men’s suits which buttoned high and/or had a tall waistcoat underneath, the unique design of full dress allowed for only a thin layer of cotton between the wearer and the elements. Concerns of contracting “pneumonia and other diseases” initially prompted the use of the under vest, a sleeveless high-buttoning garment made of warmly lined silk and worn under the shirt. A similar lining was incorporated into the full dress protector thus rendering the vest unnecessary.
A sachet (small package of perfumed powder used to scent clothes) was sometimes added to the protectors although some authorities considered this practice a bit gauche.
In both the UK and US, dress shirt protectors abruptly fell from popularity at the end of World War One, likely due to the concurrent decline in coal use.