The primary color mixing bowl set is the first multi-colored Pyrex mixing bowls set that was made. These 4 bowl sets began to be manufactured in the 1940s. They are referred to as the 400 series bowls or the Primary Color Bowls. Many Pyrex collectors consider the Primary Color Bowls to be the standard when it comes to collecting vintage Pyrex cookware.
The Pyrex Primary Colors Mixing Bowls set contains a 4 quart yellow bowl that is 10 inches in diameter, a 2 and 1/2 quart green bowl that is 8 inches in diameter, a 1 and 1/4 quart red bowl that is 7 inches in diameter, and a 1 pint blue bowl that is 5 and 1/2 inches in diameter.
Although the Primary Colors Pyrex Mixing Bowls set is not rare, it is extremely popular among collectors. As a matter of fact, this set is considered to be the most sought after. It can be quite easy to find the smaller mixing bowls in excellent condition. However, the larger bowls can be a little more difficult to find. Because of their larger size, they are more likely to be damaged or broken. These mixing bowls nest inside one another for ease of storage. Because of this characteristic, it is not unusual to find complete, four bowl sets in good condition. As with most collectables, condition greatly affects the price. If you are purchasing bowls from an online auction, be sure to request clear photographs or detailed information regarding the quality of the bowls.
Throughout the years, there have been some color variations in the Primary Color Pyrex Mixing Bowls set. Collectors should also be aware that the oldest sets are not numbered on the bottom. The mixing bowls were not numbered until the 1950s and continued to be numbered until the 1970s. Be cautious if a seller claims that a bowl set is old because it does not have numbers. It is possible to remove the numbers on the bottom of the bowls by grinding them off. It is also possible that the bowls are a newer set that was made with older molds. Sometimes, the numbers would wear off the molds and not imprint on the bowls themselves. Find out if the bowls set comes with the original box. This will help you to determine the age of the bowls and if they were originally sold together as a set. Check the thickness of the bowl walls. Bowls made in the 1940s are thicker than their newer counter parts.