INTERLINING FOR WOOL COATS

Our best recommendation to turn up the isolation and ability to keep warm in a wool coat is a wool interlining. In Danish it's called 'French Interlining', but we haven't been able to find whether this is actually the English term for it as well. French interlining is a very loosely knitted wool with a lot of airy space to isolate. It is soft and doesn't take up much space inside a coat, so it won't get bulky and rigid to work with - which can be the case if you choose a thick batting or thinsulate interlining.
The French interlining is also good beacuse it is natural fibres, so you maintain all the good properites by making a coat in wool. If you choose a syntetic fiber for lining or interlining you will make a 'shell' between you and the wool, which will reduce the breathable and isolating properites of the wool. 

Whn you work with French interlining, you can choose to use it both 1 or 2 layers, depending on how much you want to isolate our coat. Often it can be enough to use the interlining in front and back - or only the upper part of front and back - and not in the sleeves to avoid them getting too thick.  

You might have to consider going up a size when you use interlining in a coat to make more room for you inside the coat.  

Tip: when you cut your interlining, cut it according to the pattern parts for the outer fabric and attached it to the outer fabric, before you start sewing your coat. Trim it for the hemlines so you don't get double layer in the bottom and sleeve hem.
If you cut you interlining according to the lining pieces and attach it to the lining, you will loose the fleksibility of the lining and you won't have the interlining covering facings etc.  

We have included a sample of the French interlining in the sample box.

FUSING FOR WOOL COATING

Wool coating must be interfaced to keep in shape. Specially around collars, hems, facings etc., but sometimes you will also need to interface larger pieces, like the entire front pieces to get enough stability and shape. 

To interface wool coating we receommend using a woven cotton interfacing. It's a very thin cotton with glue dots on one side to apply the same way a you use regular interfacing. 
The advantage of using the woven cotton interfacing for wool coating is that you get much stability while you maintain a soft touch and allow to wool to shape without getting stiff.

We recommend these types of interfacing:  

G700, which is a heavy woven cotton interfacing, to give strength and shape for light to medium weight fabrics.
G710, which is a medium weight woven cotton interfacing to give strength and shape to medium weight fabric.
G740, which is a medium weight woven cotton interfacing with a stronger weave to give shape and strength to medium to heavy weight fabric.  

G770 is also a kind of woven interfacing but it's flexible/slightly stretchable and made of syntetic fibres. It gives shape and stability, but maintains the flexible structure, so it's great for flexible fabrics like boiled wool or heavy wool knits.  

Which interfacing to use depends on the fabric and the garment you are making. You will have to feel and try in order to choose the right one. Make a few tests and see if you get the shape, hold and texture you want. You might have to use different types of interfacing for different parts of the coat to get the best result.

It's very important that you make sure to apply the interfacing to fabric so it's attached with no folds, bulks or areas where the interfacing is loose. This will be visible on the outside of the coat, so you really want to take your time and do this very thoroughly. 

Your pattern dosn't always tell you the answer to how, where and which interfacing to use. It all depends of the fabric, so you have to make your own decisions on this.