To determine the age of a piece you need to find the type of mark and mold number (if any), the type of clay used and the correct glaze color.


One of the most important points about collecting Frankoma pottery is to identify a pieces' age according to what type of clay was used. Determining this can have a large impact on pricing an item. 

John Frank worked with clay from different locations in Oklahoma and he settled on a deposit of tan clay from Ada, Oklahoma. Frankoma used this clay from 1933 until 1954 and collectors refer to it as Ada Clay. Mr. Frank discovered this deposit of clay while teaching at the University of Oklahoma, which he used for his art classes. This clay had to be extracted from the ground similar to digging trenches. Over the years the quality of this clay declined past an acceptable level. Tree branches and other trash built up, which had to be cleared before more clay was extracted. Then, the clay had to be hauled 150 miles by truck to Sapulpa.

In late 1954, the company switched to a brick red firing clay which was several miles from the factory in Sapulpa, Oklahoma. This clay was extracted from Sugar Loaf Hill and is referred to as Sapulpa clay. A local brick manufacturer used this deposit for making bricks. This mineral rich clay significantly changed the appearance of many of the glazes, especially the rutile glazes. (Prairie Green, Woodland Moss, Peach Glow, Desert Gold, Brown Satin).

Further, during the 1980's, the clay was infused with additives which affected the color. This changed it from red to a light pink or a light orange.

Determining the difference
Many people use the "wet finger" method to determine whether a piece is made of Ada Clay or Sapulpa Clay. The method is this: Wet the end of your finger and touch the unglazed portion (usually the bottom) of the item in question. The theory is that if it is Ada clay, it will not change color because of the high firing temperature will not allow the moisture to be absorbed by the clay. If it is Sapulpa clay, it will visibly darken. This method is generally, but not 100 percent, accurate.



ADA CLAY 1933 - 1954

Light tan or honey color, usually does not darken when wet.

 Sapulpa Clay (Red) 1955 - Circa.1980

Deep Red color, became lighter as production years went on.

Sapulpa Clay (Pink) Circa. 1980 - Present

More pink or orange colored than red due to additives in the clay to make it stronger.  Sometimes so light it is mistaken for Ada Clay.

Frankoma Marks 

The earliest Frankoma pieces (1933-1934) were marked either Frank Potteries Norman Oklahoma, or with the OKLA abbreviation rather than the full state name, or simply Frank Potteries.  Some examples of Frankoma from this time period can be found with a black ink rubber stamp.  Frankoma also used the cat mark (Pot & Puma) between 1934 and 1938. 


                                                             Ink Stamp (1933-1934)

Cat Mark (1934-1938)

Between 1934 and 1954, Frankoma used an impressed mark.  Prior to a large fire at the plant in 1938 the Frankoma mark had a perfectly round ‘O’ after the fire the ‘O’ became more oblong. The round 'O' is also identified by the 'M' next to it which will have slanted legs as opposed to the oblong 0 which will have an 'M' with straight legs on it. The incised oblong 0 mark is the most common mark in Ada clay and came in 3 or 4 sizes ranging from 1/8" to 3/8" . The smallest 1/8" mark was used from 1939-1940 and got larger almost from year to year into the 1950's until 1954 when the 3/8" mark was used and the end of Ada clay production. Sometime in 1952 or 1953 was the beginning of the "stylized in the mold " mark which included the Frankoma name and mold number. These came in many sizes and continued from 1952 to the present day. In the early years it was indented into the unglazed clay, then in later years it became raised letters under the glaze.

Incised Round "O" With Slanted leg 'M' 1934-1938

Incised Oblong "0" With straight leg 'M' 1939 -1954

"Stylized in the mold" mark  Circa 1960's