Kodak Portrait Diffusion Disk

<p>So I bought a Kodak Series VI Portrait Diffusion Disk on eBay. Cool thing to have, I expect. However, when I unpacked it, the glass immediately fell out of the mounting ring. Now, nothing's broken, but the ring has a marking which side should be "FRONT". But, I now don't know if the front is the side with the circular ridges cast into it, or the smooth side, since I don't know which way the glass originally was in the ring.<br>

Anybody out there have one of these that has never fallen apart? What side has the ridges?</p>

 

<p>John, I have a Kodak Pictorial Diffusion Disk, dated 1921, numbered 3F45 on it's nice little case, but no other markings. I've used it as a diffusion disk while enlarging. The ridged/cross-hatched surface is mounted to the rear, against the lens. It's a very thick piece of glass! Hope this helps....</p>