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  1. #1
    Rafal Lukawiecki's Avatar
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    Edge-long Dimple When Dry Mounting

    I have recently changed my mount board and I am noticing a dimple on my dry mounted prints. There is a very gentle, edge-long dimple parallel to all four edges of the print, less than 1 cm (1/4") from the edge. I can only see it when looking at the print at an angle at which I can see a light reflection along the edge, otherwise it is not visible at all.

    The dimple is like a very shallow "valley" close to the edge of the print.

    I am wondering if anyone has seen this before and if there was an easy solution, like higher temperature, more pressure, or the opposite. I use Unimount tissue (made in UK by Hotpress). I place the package under two sheets of larger 4-ply mount board and there is one such sheet under the print package. The press is a Bogen 560 (aka Technal).

    Many thanks,
    Rafal
    Rafal Lukawiecki
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  2. #2
    Robert Hall's Avatar
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    Details please.

    First, can you get an image of the problem?

    What size is the dry mount tissue in relation to the print? Could it be smaller than the print causing the edge?

    What is the platen size?

    What is the mat size?

    What is the mat brand?

    Could it be the print paper? Have you tried this with another type of paper/mat combination?

    What is the temperature of the press and how long do you press the image?

    Again, to understand correctly, you have the heat platen on top of 2 4 ply mats, the print, the tissue, and then the mount board?

    Regards,
    Robert Hall
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    Technology is not a panacea. It alone will not move your art forward. Only through developing your own aesthetic - free from the tools that create it - can you find new dimension to your work.

  3. #3
    Andrew K's Avatar
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    My only suggestion is you "dry" your mount board first before putting the print on it.

    I always put the mount board into the press for a couple of minutes to drive out any moisture that may be present in the board. I then let the board cool down, and then mount my photos.

    I was taught this 30 years ago when I first started dry mounting - our workroom was not temperature controlled, and the mount boards tended to absorb some moisture from the air over time..

    I think we started doing it because we had a problem which from memory were similar to yours?
    A camera is only a black box with a hole in it....

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  4. #4
    Rafal Lukawiecki's Avatar
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    Quote Originally Posted by Robert Hall View Post
    Details please.

    First, can you get an image of the problem? [...]
    My apologies, I should have provided more detail straight away. Please see the image, it shows the dimple in reflected skylight. The dimple is gentle and only visible in such lighting.

    I always pre-dry the mount board (1 minute, with pressure) and separately the print (1 min, no pressure except a gentle 5s squeeze at the beginning). I predry them both between three larger, already warmed and predried mount boards (two above, one below). Trimming and mounting is completed within 20 minutes.

    This issue does not happen when using (a slightly thinner) Ilford Gallerie paper but only with Ilford MGIV FB glossy. The size of the trimmed print is about 11" x 15". The print is trimmed together with the tissue to their exact size on a Rotatrim, after the tissue had been tacked to the print in one place using a tacking iron. (It is then tacked in another spot to the board, creating a "Z" tack, as recommended by Hotpress, the makers of the tissue.)

    The tissue is Hotpress Unimount Classic, a fairly popular make in this part of the world, I gather. It is the more traditional type which creates the bond when hot, not on cooling down like Buffermount etc.

    The mount board is Silverprint's Conservation 4-ply (1.5mm) mount board, 16 x 20". The protective 3 sheets (one below and two above) are also the same boards but 20 x 24".

    The platen is 20 x 23" in size on this Bogen (Technal) 560 press.

    I am not sure what the temperature accuracy is as I have no confidence about the position of the temperature knob. It suggests that the temperature should be between 104 and 121 C (220 and 249 F), but I feel it is actually lower than that. Pressing with lower temperature settings caused corners to separate when bending finished and mounted prints, at the current temperature setting they seem to have better adhesion but they still occasionally delaminate when bending them outwards (repressing seems to fix that issue).

    The pressing time is 3.5 mins (shorter times led to corner separation when bending). The "project" is arranged as, from the bottom press foampad: 1 large (20x24") 4-ply prewarmed mountboard, the actual 16x20" 4-ply (1.5mm) mountboard, 11x15" tissue, 11x15" MGIV FB print, another two 20x24" pre-warmed 4-ply mount boards, hot top platen.

    It is difficult for me to describe the pressure, but it is not the maximum I could exert, perhaps 60-70% of the max possible. If I were to put my fingers between the platen and the foam, without the additional 3 mountboards, and close the press (cold naturally) the pressure is significant but perfectly bearable.

    Please note that all of the above settings used to work quite well with a different brand of mount board and they continue to work well when using Gallerie FB paper, but not with MGIV FB.

    I would be grateful for any suggestions you may have. More pressure, more/less time, higher/lower temp...? Thank you.

    Rafal
    Attached Thumbnails Attached Thumbnails Edge-long-Dimple-when-Dry-Mounting.jpg  
    Rafal Lukawiecki
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  5. #5
    Robert Hall's Avatar
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    So this is new to me so I am willing to only venture a guess and suggest that changing a few things with your setup to see if the results might be different.

    First, it looks (not trying to be too obvious here) as an edge effect. I wonder if changing the mount tissue would change this appearance of these lines. It may be due to the papers dimensional stability under the heat.

    I might suggest a couple of other things. First, I would try just one sheet of 4 ply or even 2 ply. Heating so much paper takes a lot of energy. If you only used one sheet, you could press for less time. I also think that the moisture in the paper would have less medium to travel through to be released.

    My setup uses as little material between the thing to be heated and the platen. I also use a lot of release paper, a silicone impregnated paper that allows one to easily remove the mount tissue from the paper.

    I use the press to attach tissue paper via 1 sheet of release paper, the print, upside down, tissue, one more sheet of release paper or release board (about 4 ply) and that contacts the platen. I then let it cool and trim the print, I then set the print on the board where I want it, put it back in the press with the print facing up and place release paper or board on top which contacts the platen.

    I keep in under for 45 seconds at 225 F. I keep the platen clean with naphtha and use only the smoothest surface to come in contact with the print as I have left texture in the print in the past by choosing a bad surface covering the print.

    I hope this helps in some small way.

    Regards,
    Robert Hall
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    Technology is not a panacea. It alone will not move your art forward. Only through developing your own aesthetic - free from the tools that create it - can you find new dimension to your work.

  6. #6
    MattKing's Avatar
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    I have no constructive suggestions.

    I do think, however, that "Edge-long Dimple" would be a great name for a band.
    Matt

    “Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”

    Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2

  7. #7
    Robert Hall's Avatar
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    No suggestions with _your_ first name?
    Robert Hall
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    Technology is not a panacea. It alone will not move your art forward. Only through developing your own aesthetic - free from the tools that create it - can you find new dimension to your work.

  8. #8
    MattKing's Avatar
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    Quote Originally Posted by Robert Hall View Post
    No suggestions with _your_ first name?
    Too many "t"s
    Matt

    “Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”

    Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2

  9. #9
    Ian Grant's Avatar
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    I used this tissue when it was first released by Lion Picture framing (and Hot Press) sometime in the late 1980's, I'd previously used Ademco tissue. It's a temperature/time issue causing shrinkage, I found the tissue had a lower melting temperature & required less time than the Ademco stuff I was used to. Tissues changed because people were mounting RC prints where too high a temperature damaged prints.

    My Ademco press only has high & low settings and is either full weight or nothing but I still used the high setting but cut the time substantially, that was enough to get a good bond (still all OK 20+ years later) but not transfering all the heat through the top/bottom cover boards.

    I think if that tissue gets too hot it gets into the board and shrinks it pulling from the edges (capillary action) I did get the same when I first tested it. Hot Press make their own presses which use glass so don't get as hot as my Ademco with it's cast iron parts.

    Ian

  10. #10
    Rafal Lukawiecki's Avatar
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    From your comments it sounds like I should try using less protection above the print and under the platen, perhaps just 1 board instead of two, and perhaps shorten the time. When I mounted inkjet prints earlier in the year (quite successfully), I had to use lower temp but using less protection above those prints showed that the heat pattern was not uniform across the print surface. Adding the extra board (so in total 2 x 4 ply) seemed to make it quite even heat, which I assumed would be a good thing for FB prints, and which is how I had always done it before.

    I wish there were not so many variables at play here. It would be so much easier to nail down the issue... I suppose I should try higher temp and shorter time, or, as some suggested, placing the print "upside down", that is print below the tissue below the mount board.

    If anyone else reading this sees the picture and feels "a-ha" becaue you had seen this issue, please let me know. I am facing a longish mounting session this week, 18 prints to do, and I really would love to get this solved for now, and I suppose for the benefit of the community.

    Many thanks,
    Rafal
    Rafal Lukawiecki
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