cutting prints & dry mounting question

My usual procedure for pre dry mounting bw prints is thus: After drying, I flatten my prints via the heat from a dry mount press. As I prepare a print for dry mounting to an archival board, I tack a piece of mounting tissue of approx. size to the back sided of a print leaving at least one edge of the print a la natural or left alone as is. This "left alone as is" is my guide for trimming the print with a 36" Rotatrim, using that one side as my "rule". My reasoning is that if one side of the paper (print) is "straight", then 2 other cuts will make the print square & then the 4th side is cut as well.

My question is: after the print drys, I am assuming that the print is still rectagular in shape & straight on all four sides. Is that true or does the paper take on weird sizings due to shrinkage in the drying phase????? If straight sizings is off, then my dry mounting cuttings would be off as sometimes I suspect.

I hoping I am making myself clear on this issue. If not, please ask for a rephrasing. And if you follow similar procedures, perhaps make suggestions.

I'm not sure I understand what you are saying, but let me describe what I do. I tack the dry mounting tissue at several points, starting from the center but leaving the corners loose. I then trim it either with a rotary paper cutter or, more often, with a straightedge and an Exacto knife. I use the grid on my cutting mat to ensure rectilinearity on all four sides. I then tack two or more corners to the mounting board and put the whole thing in the dry mount press and mount it. For prints larger than my press, I do the pressing in four sections.

My dry mounts have held up quite well. I don't believe that after mounting there is any significant change in size as it cools. If you sometimes see some lack of rectilinearity, I would guess it is due to a failure to trim it that way to start. It is impossible to get it absolutely square, so slight errors should be tolerated. But I suppose some of us are more tolerant of that sort of thing than others.

Drying should not cause any irregular shrinking. To check for square, measure the diagonals. If they are the same, it is either a rectangle or a trapezoid.

Tim,,

A trapezoid is a quadralateral with two parallel sides. It need not have equal diagonals, unless the two nonparallel sides make equal angles with each of the parallel sides. Also, there are other quadralaterals with equal diagnonals which are not rectangles or trapezoids. Imagine for example two equal kite struts tied together. You can clearly tie them anywhere you please along their lengths and then construct a kite about them with a relatively arbitrary quadralateral shape.

If a quadralteral has equal diagonals and each pair of opposite sides is equal in length, then it is a rectangle. So it is possible to check this way if you make enough measurements.

The problem may be that you trimmer is not squared. I have two rotatrim trimmers, and both were off. I could not find a way to align the straight edge to the cutting edge, so using double stick carpet tape I put down a metal ruler to align the print. All my cuts are now perpendicular.

Mike

Mike,

I seem to remember from an old Rotatrim we used to have that if you peeled off/up one of the "rotatrim" (I think it was) labels there was an adjustment screw underneath - but it was a while back now, and it may just have been on that one model?

tim

I would think you should start your search for an evenly trimmed print with a look at your easel. It may be making prints that are not quite rectilinear. My bottom-of-the-line 14X17 Saunders easel is miserable in this regard; I've got to measure everything and tape down the blades to keep things straight.

Equalize the diagonals of the print frame when adjusting the easel blades, as discussed above, to be sure you are starting with a 'square' image.