Penguin Pottery - 8-Color Underglaze Variety Set (4oz Jars), Cone 04 to Cone 6 Review (2026)

Who benefits from this range

This set suits potters who fire across more than one range, since the cone 04 to cone 6 rating means the same jars work whether a piece is heading into a low-fire electric kiln or a mid-fire stoneware load. That flexibility matters for classrooms and shared studios where different students or projects target different cone ranges but everyone wants a common palette. It also fits potters transitioning from low-fire earthenware to mid-fire stoneware who do not want to rebuy an entire underglaze set when their firing schedule changes. Potters who only ever fire one specific cone and want the widest possible color selection at that single cone might find more choices in a larger, single-range set instead.

What is in each jar

The set includes 8 colors, black, white, red, orange, green, yellow, blue and purple, in 4-ounce jars, twice the volume of many 2-ounce sampler bottles from other brands. Penguin Pottery makes the line in Vermont and markets it as lead-free, non-toxic and food safe, with a lifetime warranty covering refunds or replacements if there is a problem with the product. The maker positions these colors as a base palette meant to be mixed and layered for custom shades and added depth, rather than a fixed set of finished looks, which fits potters who like building their own combinations more than reaching for a pre-mixed specialty color.

Using it day to day

Because these underglazes span cone 04 to cone 6, always fire a test tile at your specific target cone before committing a full piece, since color intensity and finish can shift somewhat across that range even with the same jar. Brushing two or more coats gives the most even, opaque coverage, and layering colors while wet lets you build gradients or blended tones directly on greenware or bisque. Firing must happen in a calibrated pottery kiln, not a kitchen oven, since underglazes need controlled heat work to mature and bond properly. The larger 4-ounce jars mean less frequent refilling for small studios or classrooms working through a shared set.

How it compares with other underglaze sets

Against AMACO Velvet Underglazes, a 12-color set in 2-ounce jars rated cone 05 to 10, this Penguin set offers fewer colors but larger jars and a narrower, more mid-range focused firing window. Speedball's own 001085 sampler pack gives 12 colors in 2-ounce bottles across a wider cone 06 to 10 range, which suits potters chasing more shades over raw volume per jar. If color count matters more than jar size, a 12-color set edges this one out, but if you want fewer colors with more product per jar and a firing range built around cone 04 to 6, this Penguin set is the more efficient buy.

Bottom line

This is a solid starter or classroom set for potters who want a flexible cone range and generous jar sizes over a long color list, backed by a maker warranty that removes some of the risk of trying a new brand. The 8 core colors cover the basics for layering and mixing rather than offering many pre-made specialty shades. Potters chasing the widest possible palette in one purchase should look at 12-color sets instead, but for dependable coverage across low and mid fire in one box, this set does the job well.

Frequently asked questions