Pyrex Percolator on stove?

Pyrex percolators made after 1940 were not intended to be used directly on a heating element as stoves made after 1940 had a higher burner heat level that those made in previous years. (Presumably, those made before 1940 were placed directly on a burner.)

The Pyrex percolators I remember had a wire 'grid' or 'heat spreader' that was to be placed on the burner and then the percolator sat directly on that. If memory serves me correctly, they came in a variety of shapes. See below for an example.

I have a Pyrex 7756B (4-6 cup percolator) that I purchased about a year ago. I use it daily on a gas stove. Mine came with the heat spreader, but I've never used it as the instructions on the packaging state that it's only necessary on an electric heating element. From the envelope the heat spreader came in:

IMPORTANT

Heat Spreader Grid for use with PYREX® Brand Rangetop Ware. The enclosed heat spreader grid MUST ALWAYS BE USED when PYREX brand items (image of the Flameware logo, then on bottom) are placed on ELECTRIC RANGES. The guarantee does not remain effective if this item is used on an electric range without a wire grid or if it is allowed to boil dry on any range.

1. Place the wire grid on top the electric heating unit and the PYREX brand rangetop item on top of the grid. (This is not necessary on gas.)
2. Use low to moderate heat. Sticking of food indicates too much heat
3. Always put liquid in a PYREX brand rangetop dish before placing it over direct heat on top of the range.
4. ALLOW HOT DISHES TO COOL BEFORE ADDING LIQUID.
5. Handle a hot PYREX brand dish with a dry cloth and never set hot PYREX brand dishes on wet surfaces.
6. DO NOT USE FOR DEEP FAT FRYING.

Capitalizations above are the original writer's. It's worth noting that entire thing is printed in bold, red type.

I have a couple of them, and have used them on both gas and electric stoves with no trouble. Using a heat spreader isn't a bad idea, but I have found no issues using them without. I do not even know how old mine are -- pre-1940s or not -- but either way, they work really well.

I think I have the definitive answer to this question. I found the Pyrex percolator at the Corning Glass Museum. It came with a metal heat diffuser. If you scroll through all the pictures (links to the other images are to the lower right of the main image), you’ll even see the paper sleeve the diffuser came in.

If you search the museum collection for glass percolator, a number of them come up and most have a metal heat diffuser in the full set.

We’ve been using our vintage coffee pot on an electric stove without a diffuser for a week. It hasn’t damaged it but we’re now using the diffuser that came with our Chemex coffee maker.

Mine blew apart over medium-high heat. Glad top burner.