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Block Fuse and Spot Fuse Tutorial

Block fusing your facings is a great little industry trick that anyone can use.

Why? It is more accurate to cut out facings from a pre-fused piece of fabric, rather than cutting the fabric and interfacing separately and then trying to fuse them together. They don’t always stay on the straight grain, they may shrink and it’s just so fiddly!

When? On facings, collars, pocket flaps, on any pattern piece that requires the WHOLE area to be interfaced. Maven Patterns are marked as CUT 1 PAIR SELF + BLOCK FUSE,  but other sewing patterns may be marked ‘cut 1 pair fabric + cut 1 pair interfacing’. This is an especially fabulous method to use for hideously slippy fabrics!



It’s really very simple. When laying up your garment to cut out, leave an extra couple of centimetres around your pattern pieces (a bit of wiggle room and enough in case of shrinkage when fusing) and roughly cut out the fabric. Ideally, make sure you use a piece with the selvedge on, so you can keep everything on grain.


Should you be cutting a front facing on the fold; cut out roughly again and snip with your scissors along the folded edge. You’ll have a marker to re-fold on the grain after fusing. I find marking with chalk etc tends to disappear under the iron.


Do a test piece first, don’t burn your fabric!

Cut a piece of interfacing very slightly smaller than your fabric, so it doesn’t overhang your edges and stick to your ironing board cover. Placing a cloth over your ironing board first is a good idea too. It saves the cover from gluey gunk which can transfer on to other garments – this is that voice of experience you hear of.

Lay the interfacing with the GLUE SIDE to the WRONG SIDE of the fabric. Cover with a cloth and PRESS into place. Refer to the manufactures instructions but heat, steam and pressure are usually the best combo. Don’t be tempted to drag your iron over it either, it will stretch and shift. Just place and press with your iron. I usually allow it to cool before turning over and pressing on the right side too. You can do quite large pieces if necessary, but it is a lot easier to manage if you use smaller pieces and you are less likely to get creases and bubbles in the interfacing.


Now just cut out your facings and collars.



When and why? If BLOCK FUSING is used to interface an entire piece, how do you strengthen one small area of a garment? That’s when you SPOT FUSE.You might, for example, want to add a patch pocket on a jersey t-shirt. You know that each top corner is going to be a really weak point and wear badly after a few washes. Spot fusing means you can add a small piece of interfacing for extra stability but only where it’s needed. The pocket mouth on The French Dart Shift and the Kitty Dress, and the neck opening on The Wendy Smock all need a little extra reinforcement with fusible interfacing. We don’t need it all over the garment- just in a specific SPOT .


So easy! Cut your pattern piece out in fusible interfacing only as directed (marked on Maven Patterns as CUT 1 PAIR FUSIBLE INTERFACING). Apply directly to the area of your garment that needs extra support. That’s it! 

*a little note…

I’ve called this SPOT FUSING for the last 30 odd years while working in the industry. But, just to confuse you, sometimes the term ‘spot fuse’ is also used to describe attaching fusible interfacing to the fabric when you block fuse a LARGE area. Interfacing is difficult to attach over a large area without it twisting, bubbling or other such delights. Lifting your iron and placing the tip down in various places working from the centre outwards is a good method, basically, gently STEAM BASTING the interfacing into place rather than the attempting to do the whole piece in one go.