diff --git a/NOTES_ON_OPTICAL_PRINTER_TECHNIQUE.md b/NOTES_ON_OPTICAL_PRINTER_TECHNIQUE.md
index 8280dd9..f1c1709 100644
--- a/NOTES_ON_OPTICAL_PRINTER_TECHNIQUE.md
+++ b/NOTES_ON_OPTICAL_PRINTER_TECHNIQUE.md
@@ -302,4 +302,50 @@ Or this method: register in the printer gate a bipack of the original with any f
 Determine how much vertical adjustment separates their framelines.
 Make that puch adjustment to the aimframe setup.
 
-The framelines of the original can always be eliminated from the print by setting the magnification slightly greater than 1.
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+The framelines of the original can always be eliminated from the print by setting the magnification slightly greater than 1.
+
+## EMULSION POSITION
+
+A priori, a film of an alphabet could be any of these eight ways.
+
+**![Graphic depicting eight strips of film with letters F and G oriented and labelled](#)**
+
+Each sketch shows emulsion facing out.
+For double perf film there are only four ways.
+The a and b ways become the same.
+
+Camera original is (IIIa).
+
+A contact print from camera original is (Ib).
+A contact print from a contact print from camera original is (IIIa) again.
+Etc.
+
+All the others are shams--either optical printing errors or else films of alphabets somehow reversed.
+
+Given a double perforated (I), (II), (III), or (IV) it is easy to make a double perforated optical print which is any of the four.
+
+Single perforated films are a pain in the side.
+Given, for example, (IIIa), it is possible with a usual optical printer to make either (Ib), (IIb), (IIIa), or (IVa), but none of the other four.
+These could be made via a double perforated intermediate.
+With a prism or other image rotator, or a special reversed gate, it is possible to convert any of the eight ways to any of the eight ways.
+Figuring out how to do these is a good exercise for the student.
+
+The two non-sham emulsion positions are sketched again,
+this time with emulsions facing in shown dotted.
+
+**![Two graphics depicting CAMERA ORIGINAL and CONTACT PRINT FROM CAMERA ORIGINAL](#)**
+
+Notice that when pictures "read right" single perfs are on the left, and "before" is above.
+
+Notice that camera original reads right with emulsion facing away. 
+Contact print of camera original reads right with emulsion facing toward the viewer.
+
+Except when optical printing is done in alliance with contact printing, it is usual to maintain emulsion position through all optical printing steps. 
+Starting with camera original each generation is again (IIIa).
+For this there is a simple rule.
+
+> To reproduce the emulsion position of the original, insert it in the printer gate with emulsion away from lens, heads up, running upward.
+
+Optical printing "through the base" does not degrade image quality.
+
+The optical printer can also imitate the contact printer, if the original is inserted in the printer gate with emulsion toward the lens.
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