A few hints for using interfacing...

Using the correct interfacing -and the correct application of it - can be the difference between a "home-made" and "hand-made" bag. Here are a few hints for success...

1. Use good quality interfacing. Cheap interfacing is often more trouble than it's worth.

2. You need a good iron. One with a lot of heat and steam, and a reliable thermostat. I don't have any particular recommendations (but I'd love to hear if you do). I go through loads of irons, and the only recommendation I have is "don't spend less than $60" (AUD).

3. Remember that lighter interfacings are more heat-sensitive than heavy interfacing. Light to medium-light interfacings don't like more than a COTTON setting on your iron - otherwise they'll shrivel up and wrinkle your fabric. Heavier interfacings like a HOT HOT HOT iron, lots of PRESSURE.... and STEAM is also highly effective (I don't care what the books say).

4. Press your fabric before you fuse interfacing to it. Failure to do this may result in unwanted permanent wrinkles!! (Perhaps that's what happened to my FACE...???).

5. Double-check that you have the GLUE side down to the back of the fabric. It's usually shiny or grainy. A plastic feel. If it's the the wrong way around you'll either make a mess of your iron or interface your pressing cloth.
6. Use a Rajah Cloth to protect heat-sensitive fabrics from the iron when you're pressing heavy interfacing to it. I often use (an old) one under the fabric and (a new) one over the back of the interfacing - this protects the fabric, the ironing board and the iron!
7. Press in a DOWNWARD direction. Don't slide your iron around while you're pushing down on it, or the interfacing might move and fuse in the wrong place. Hold the iron down for 5-10 seconds before gliding it gently to the next unfused area... hold it down again. Shoot steam through if it's being particularly obstinate and refusing to stick. If you see bubbles like this... STEAM AND PRESS them down!!!8. Once the interfacing is stuck into place, give the fabric a really good press from the right side. This will iron out any remaining bubbles and smooth the surface of the fabric.
9. If you do a LOT of interfacing, you might consider something like an Elna Press. (I bought mine on Ebay for $76 (!!) but they can be pretty pricey if you buy them new). They make it SUPER-EASY to fuse evenly.... you press your fabric, line up the interfacing.... Rajah Cloth if necessary....

...close the lid...
....see the difference (below) between the fused and un-fused bits..? You have to move larger pieces around a little to get all the area covered.
Close the lid again, then ... oooh-ahhh... nice and flat!
I have to add at this point, that despite having made my living from making clothing, hats and bags for close to twenty years, I only bought the Elna Press this year. I'm still in the honeymoon stage with it!!!