Finally we have reached the stage of the foam. I will keep it short otherwise it may be a boring story. There are different types of foam. The most common in a furniture upholstery are: Polyether and HR Foam.
Polyether is the cheap version and then the more expensive HR foam. I only use HR foam myself. Yes, that is more expensive, but will also last longer. If I refurbish chairs or benches for a client, I want them to enjoy them for a long time and not be on my doorstep after half a year with the complaint that there is a pit in the seat.
The below info is for the Netherlands, other countries have other regulations and other specifications and names in regards to fire safety and mass per unit volume.
The foam is indicated by the abbreviation SG, which stands for mass per unit volume. With HR foam the abbreviation stands for High resilience. And just something that can be important. The fire safety. I only use foam that also has a fire-retardant certificate. Certainly if a number of Martin Visser sofas for a restaurant, for example, would have to be refurbished.
I used HR SG40 Firm for this Martin Visser sofa. Why firm and not medium quality? Well you want the corners to be nicely sharp and the softer the foam the rounder the corners become. That’s why.
But what do you use for what? Well that depends entirely on the wishes of the customer. But to give you a bit of a guideline:
SG 30 to SG 35 is used for backrests
You use SG 40 to SG 43 for seats.
Then the dacron also called fiber fill or synthetic white cotton, polyether wrap. It comes in different weights. I generally use 100 grams. Of course also with fire certificate. I almost hear you ask, why should I use dacron? I’ll tell you. It protects the final fabric against the cells of the foam. You could see it as small barbs that grab into the material. I’m exaggerating a bit now. It also makes the fabric easier to process over the foam and if you take a thicker type, for example 200 grams, that ensures a nice rounding on the edges.
Just before you start gluing, you always spray foam on both sides. Dacron with gluing on one side. I will also make a separate blog about types of adhesives. But buy an adhesive spray specially for foam. For example at a upholstery shop in your area.
The seat and back of a Martin Visser sofa are both 10 cm thick in total. Measured from the bottom of the wood to the foam.
You can switch the subtitles in the video on and off with the wheel in the lower right of the video. Enjoy watching.