Polyurethane Foam Association

Definition - A vertical seam is a seam parallel to the same planes of the vertical edges of the seat cushion. For the purpose of this publication, a seat cushion shall be defined as the primary foam core excluding ears, tees and flares. It has been found that gluing together two pieces of foam with similar densities and IFD's is an acceptable method for constructing cushions for the upholstered furniture industry.

The adhesive seam task group conducted a sitting test at the May 1991 meeting of the Joint Industry Polyurethane Foam Standards and Guidelines Committee. A panel of committee members sat on cushions with front to back glue seams joining foam pieces with two different IFD's. The purpose of the sitting panel was to determine what IFD difference was discernable by the average person when sitting. The following cushion types (constructions) were used in the sitting test:

CUSHION ID	WRAP/N0WRAP	LOW IFD	HIGH IFD	IFD DIFFERENCE
A	F2	32	33.8	1.8
B	NF2	32	33.8	1.8
C	F1	31.5	35.5	4
D	NF1	31.5	35.5	4
E	F3	27	36.5	9.5
F	NF3	27	36.5	9.5

Participants were asked to sit and evaluate each cushion as follows:

-- No variation in feel
-- Slight variation in feel
-- Large variation in feel

The results were as follows:

CUSHION ID	WRAP/NO WRAP	NO VARIATION	SLIGHT VARIATION	LARGE VARIATION
A	NF	27 (96.4%)	1 (3.6%)	0
B	F	16 (57.1%)	12 (42.9%)	0
C	F	15 (53.6%)	10 (35.7%)	3 (10.7%)
D	NF	15 (53.6%)	8 (28.6%)	5 (17.9%)
E	F	8 (28.6%)	15 (53.6%)	5 (17.9%)
F	NF	7 (25%)	11 (39.3%)	10 (35.7%)

Joint Foam Industry Guideline - The following recommendations are to be used to make satisfactory glue seams:

Maximum of one vertical seam, from front to back, per cushion.
For seat cushions, do not exceed 4 pounds IFD variation between the two glued pieces of foam.
The adhesive should be applied according to the adhesive manufacturer's instructions and recommendations by foam type, e.g., conventional, filled, HR, etc.