Greta Jalk chair cushions  

A question for @spanky.

Thanks for the bat signal, herringbone!

NMPC:  do you have the original cushions so that you can tell what the original foam was?  Danish manufacturers used latex foam through the early 60s at least, but i've seen some urethane foam too from that era.  You can't go wrong style-wise using the same type of foam as the original but there are other factors to consider.

First, the only latex foam available now is pincore, meaning the liquid latex is poured over a bed of steel pins.  This is how they vary the density; bigger diameter pins result in softer foam and smaller diameter ones result in firmer foam.  Softer has more air space and firmer has less air space.  Hope that makes sense.  

The problem with this is that a lot fabrics don't bridge the holes very well.  You can use upholstery batting (1/2" to 3/4" thickness--NOT the fluffy poufy stuff) to mask this.  Batting must be glued down with spray adhesive like 3M (do this outside, preferably with a respirator.  The fumes are awful.)

Latex foam is also more expensive.

The alternative is urethane foam but don't get the green stuff sold in craft/fabric chain stores.  They charge a lot for it and it's poor quality.  I used to get my foam from a big local upholstery supplier but they closed down.  Now i get it on ebay from a seller called closeoutfabricsusa and have been pretty happy with the quality.

Use one level firmer on the seat than on the back, otherwise the seat will feel too soft or the back will feel too firm.  The seat bears most of the weight of the sitter.  The back doesn't have to be as firm.

I cut foam with a serrated bread knife (not electric).  I mark the cutting line with a Sharpie and straight edge, then press the knife blade straight down into the foam on the line starting at the far edge.  Using light to moderate pressure, I draw the knife slowly towards me, keeping the side of the blade perpendicular to the top surface of the foam.  (Firm foam can take more pressure; soft foam will compress before yielding to the cut so use less pressure.)  A 2" thick foam takes 2-3 passes to cut all the way through.  

For 1" thick foam I just use a new safety razor blade.

If you have any other questions, just ask.