about the only thing that (might) happen is maybe a little build up on your needle- it's not going to do anything to your machine & if you do find it's gumming up your needle all you have to do is put a little (drop) of machine oil on a paper towel & wipe the needle down---that will keep any build up from happening- works for iron on fusables--the glue tends to be (cleaner) to work with than fusables.