Cushions - Please Settle Once and For All!

[jojo]

Ok, it's not very often that I have to make a cushion that's not a boat cushion, so here's my dilemma.

I'd been told long ago that to make a cushion from scratch, measure your area, then add an inch to the length and width and cut the foam at this dimension. Then cut your fabric the same length and width as the foam, the idea being that the seam allowances will suck the foam into the correct size and the cover will be nice and tight.

So my question is: Is this the right advice, or should I be doing it differently? I'm a bit nervous because it's a really long set of cushions (100" long) and super expensive fabric, so I want to get it right the first time.

Seems like every time I read something, the advice is different. I know all of you do excellent work, so I'd really appreciate hearing your input.

Thanks,
Jo

[sofadoc]

You're right. Everyone does do it a little differently. Here's what I would do.

Because it is such a long span, I would add a full inch to the 100". Better to be a little snug, than look a little short.
Assuming that this is some type of window cushion that is around 24" or less from front to back, I might only add 1/2" to THAT dimension. In other words, if the cushion is supposed to finish 100 X 18, I would cut the panels 101 X 18.5.

It certainly won't hurt to cut the foam 101". You can always trim it a little if need be.

[bobbin]

I usually work from patterns.  The pattern is the exact size of the desired cushion.  I add a 3/8" seam allowance all around when I cut the fabric.  I add 1/2" all around when I cut the foam. 

As Sofa. pointed out, I will often add a bit more if the cushion is very long and there is no batting to be used.  When I assemble the cushion I take a 1/2" seam allowance.  Over time, I've learned that this formula accommodates the "pouf" factor, the amount the foam poufs out the boxing. 

The dreaded pouf factor has bitten my smart ass a couple of time on yacht interiors... when too much pouf has made a series of salon cushions "buck up" and not sit into their defined area nicely.  Make sense?

[MinUph]

And yet another opinion...
  Standard seat cushions I cut 1" over sized to the pattern. But when I get a long cushion I don't add a full inch to them. If your wrapping with dacron it will take up the difference. If you cut 1" longer than the pattern I've found the filling will not lay flat. Unless your buttoning it then the inch is fine.

[Mike]

[Grebo]

I do like bobbin, 1/2 " all round, except on curves like next to the hull then it's spot on.

Suzi

[ajlelectronics]

Interesting. The cushioning I have done using upholstery fabric has always been cut 1" smaller than the foam. A wrap of Dacron and it fills out nicely.

[sofadoc]

Well Jojo, you asked us to "settle it once and for all". And you got 4-5 answers that vary somewhat.

Batting/no batting........buttons/no buttons.......and the fabric itself are all variable factors that different upholsterers approach differently.

I could do that cushion with 1/2", 1", or zero seam allowance, and still make it come out right depending on how I adjust my foam/batting/buttons.

I would still suggest that since you are new to this type of cushion, and a little nervous because the fabric is pricey, go with the 1" allowance. You can always cut it down if you have to. Then you'll have a better "feel" for how you want to do the next one.

[Joys Shop]

because the fabric is pricey, I would make a mock up of the cushion with a fabric that is very similar in weight, feel, and stretch  of the final fabric.   
then all the measurements would be tested

This mock up cushion could be used like a muslin and then it can be put inside the final cushion if you want

[Mike]

Interesting. The cushioning I have done using upholstery fabric has always been cut 1" smaller than the foam. A wrap of Dacron and it fills out nicely.

ive never tried that I always cut the shape of the foam adding a 1/4" all aroung for seam allowance and the boxing I cut the same as the foam  for tautness' if 2" foam 2" boxing

[fragged8]

lots of methods but has anyone mentioned the look you are after with your chosen method.

cushions cut loose and then wrapped in batting usually look more rounded and puffy.
cushions made tight by adding 1/2" foam to the patterned size generally look flat and hard edged.

Rich

[kodydog]

Rich makes a good point. Some customers are, should I say, rigid and that's the way they like their cushions. On the other hand a big over stuffed club chair just begs for a cushion with a foam core inside a feather casing. Both cushions would be cut slightly different.

For your boat cushion I assume your using foam wrapped with Dacron. Your method is the one I would use except now fabric comes into play. A lot of the stuff coming out of china is very stretchy. Vinyl will work different than a micro-fibers.

Then there's the question of foam. A softer foam will have less push than a firm foam. There is a lot to take into consideration.

And even then, for me anyway, you still get the odd cushion that just doesn't quite fit. Event though you followed all the rules. It really PO's the sewer. I've watched several upholsterers try different methods and they all have the occasional redo.

You could do a mock-up like you suggested and this may be a good starting point, but if the fabric for the mock-up is different than the fabric used for the finished product you may experience a different outcome.

I'm not sure if there is a true and tried method for a perfect outcome every time and the thing is, unlike manufactured furniture, for the typical upholsterer its a one shot deal. Especially when using expensive fabric like you said.