Dry Mount Problem - Ripples in large prints

[Jim-wy]

Hello,

I'm using a Seal Masterpiece 210M dry mount press. When dry mounting smaller images (8x10) I have had pretty good success, some rippling but usually a good clean press. When expanding to larger prints, 18 x 12 or prints that I need to press in 2 or more sections I tend to get a ripple in the photo (bows out), sometimes several.

I'm using 'Expression ColorMount Dry Mount Adhesive' and I am mounting to mat board. The recommended temperature is 190° and I've got it set slightly above 200° which reads about 190° on the thermometer.

Below is a snapshot attempting to show the bow effect. Does anyone know what causes this and how I can avoid it? I am using a Seal Colormount Coversheet both above and below the media. I am using new 'DK' colormount perminant dry mounting tissue. I tack the tissue to the photo on one side, trim the photo & tissue, then position the photo on matboard and tack just one spot on the other side of the tissue to the mat board before pressing it.

Suggestions will be appreciated.

DryMountRipple.jpg (144.25 KiB) Viewed 2948 times

Sincerely,
Jim

[prospero]

Hi Jim.

That type of press (Think it's termed a 'soft-bed' press) is little used in the framing industry, At least in the UK.
I don't know of any framer who has one. Most would use a vacuum press or a jetmounter (roller).

Not sure how good they are for bite-by-bite mounting. With the similar hard-bed presses you use a thin metal sheet
to disperse the heat on the edges and a foam blanket to even out the pressure on the 'hills and valleys'. These machines
are largely obselete, although I still have my old HB press which comes in useful now and then.

It's a bit of a lame answer, but if you want to mount large items reliably, get a vac press. The disadvantage of a vac press
is the size of item to be mounted is strictly limited. You can get quite big ones though.

[Jim-wy]

Thank you Prospero,

Any insight is helpful - Thank you. I like the idea of a vac press but it is not likely to happen in the near future - this was donated by a good friend who has moved out of the area and has had good success with it. Your description is right on - you know what I have. I'm going to check temperatures, thickness setting, and see if I can figure it out.

I appreciate the comments,
Jim

[Steve N]

Is you machine set into the workbench, so it is at the same level as the bench, or do you have supports on either side of the machine. As you will find that the mountboard will bend down on either side of the machine if not supported, thus when doing it in 'Bites' , the bit you had just pressed , when moved out and passed along, will bend when cooling, so when laid flat later, this will make the tissue bubble up because it has cooled in a curve, so when flat will come unstuck. I had the same problem over 25 years ago, until I built up the bench to the same hight as the flat bed , so supporting the work before and after pressing, never had a problem after.

[Jim-wy]

Hi Steve,
I have made that mistake and will support the matboard outside the press next time I press multiple bites - thank you for that suggestion. What I'm trying to press right now is 18x12 photos on 24x18 matboard. The print is fully within the press and a couple inches of matboard hang out. I press for about a minute but have varied my times in trials, then move the mount to a flat table and quickly cover it with a piece of smooth granite that I can barely pick up. I can see the ripples before it is covered by the granite so it's something I'm doing at the press. I have had good results and they look great - but they have not been consistent and my last handful of attempts at those same settings have had the 'ripples' in them.
Jim

[prospero]

Have you tried pre-drying the mounting board in the press before using it.

Just a thought.