On 20 Mar, 19:02, Bob Gentry wrote:

When I used to work in a local gage test shop (pressure, temperature,
etc.) we made our own dry ice blocks for temperature tests. This was
done by inverting the CO2 bottle and running the output through a two
piece block with a filter screen on the exhaust side.

That's regarded as bad mojo locally. I've never heard a good
explanation why though, other than that the gas supplier would rather
rent you yet another cylinder, this one with a dip tube running down
inside.