Auto body repair & detailing: welding new restoration with new panels, brian a hall, allexpert

Question
I am an Master auto tec. And have recently been told that I cannot weld through my 1/4 punched out holes for attaching a new floor pan on an old Duster, If I sand blast before weld.  Because it is said that impregnates the steel with silicon. I have done this for 30 years and have never heard of this before. I was told this by the person who I am helping restore his car. Said He read this from the Miller web sight. Have the rules changed on welding prep? I all so used to Be an ALLexpert before I retired. If You can help Me that would be great
         Thank You
         If You cannot help me, Please help me get in contact with someone who can?  Thanks again
         Brian A. Hall

Answer
Hello Brian
Excuse the delay
I have never heard of this  'impregnates the steel with silicon' notion before this email. Do the job the way the way you have always done it and the way that has always worked for you.
I hope this bit of objectivity helps you
Dan