How to make a concrete seat

Step 4.8   Releasing the seat form

Slip a piece of boardA piece of sawn, or dressed lumber of greater width than thickness. Usually 19mm (3/4") to 38mm (1 1/2") thick and 75mm (3") or more wide. under the middle of the seat form.

Of course, you will need someone to tilt the seat back while you do that.

The board can be 1″ (25mm) thick more or less, it doesn’t really matter, and 20″ (500mm) long x 6″ (150mm) wide.

Stand on the two sides of the seat form and give a little bounce up and down.
This will break the seal between the concreteA mixture of sand, gravel, water and cement which hardens to a stone like condition when dry. and the form. You will visibly see the seal breaking – a slight parting between the concrete and the form.
The seal will be more of a suction seal, rather than an adhesive seal, because of the release agent. Standing on the form and giving a little bounce will break that seal.

Now stand on the two ends (as opposed to the two sides) and do the same thing.

Now the concrete seat should easily lift out of the form.

If by any chance it does not, then turn the whole unit upright and knock one end of the seat form up by hitting it from underneath with a hammer.

You only need a little bit of air in to break any suction hold.

Mmmmmmm. Looks pretty good to me.