Steam distorts the fabric?
 

My sister and I are sewing. She tells me that the steam in my iron is distorting the fabric. True? But, I like how flat steam presses my seams and blocks.

It will if you move your iron around, not if you just set the iron on the seams. I know someone will come along with a different opinion.

I'm with Jingle ........ it would appear that your sister may be "ironing" and not "pressing".

Ahhh, another great quilting debate. Everyone has their own opinion. If you have been using steam and your blocks aren't distorted, I say keep doing what you have been doing. I use the burst of steam on my iron a lot. I'm happy with my less than perfect quilts and have no intention of changing. It is up to you to decide what you want to do, much like pre washing or using starch or that many other personal decisions we all make in our own quilts.

I used to use steam, but now I prefer to use just a very hot iron. It flattens my seams just fine. The problem with steam is that it is easier to distort the fabric, especially if you have a heavy hand and/or are ironing on the bias. Some people can iron with steam and get no distortion; others iron with steam and get a lot of distortion. Probably the easiest way to tell is to sew together some half-square triangles, then press half with steam and the other half without steam. If your steam ironed blocks are not square and your dry ironed blocks are, you know that steam is contributing to distortion.

I try to press/iron with the grain. That seems to minimize distortion.

I've been taught to only use steam when I'm first ironing the fabric to prepare it for cutting. The wetting & de-wetting process does typically cause the cotton fibers to shift. Of course, there are many factors that will impact how much that will alter/distort your edges/seams. If you are using steam, it does help to allow the piece to completely cool & dry in place before you pick it up after pressing. As others have stated, try to go straight down (press), rather than moving the iron around. If you heavily starch the fabric at the beginning of your project, that will help to limit how much the fibers shift. And, if your pieces are cut on the straight of grain, rather than on the bias, the distortion will be much more limited -- especially if you use good quality fabrics.

I will say that I seem to get better results with a mini iron for pressing seams. It does not use any steam & is lightweight, thereby minimizing the distortion that occurs when I move it slightly to make sure the top of the seam is pressed open.

That said, the main reason I switched to a dry iron in the first place was to avoid steam burns as I was trying to hold down my fabric. If you're happy with the results of steaming your seams, there's no reason to switch. Clearly, you have a technique that is working for you. :)

I always tell my classes that it's not the iron that causes the problems, it's the "ironer".

I use steam until the iron runs dry, then I don't :)

I use steam most of the time but know how to do the up and down----not pushing it across a block or part of a block.