...the chair in the kitchen is too large...

I made a hi-density foam jobbie, custom-fit to me and to the relevant chair. It's working wonders.

I made it from two pieces I cut and wrapped in sheeting which I then tufted to keep all the layers together:

1 foam upholstery wedge such as raises the head of a twinbed
1 foam bolster (half the length of a twinbed), sliced into two half-rounds-- one for head and one for back.

This backrest supplements the built-in back the chair's previous owner had compressed to fit HIS back, which then did not fit mine.

~S~