Edge-long Dimple When Dry Mounting

Discussion in 'Presentation & Marketing' started by Rafal Lukawiecki, Nov 18, 2010.

  1. Rafal Lukawiecki

    Rafal Lukawiecki Subscriber

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    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
     
  2. Robert Hall

    Robert Hall Subscriber

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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,
     
  3. Andrew K

    Andrew K Subscriber

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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?
     
  4. Rafal Lukawiecki

    Rafal Lukawiecki Subscriber

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    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
     

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  5. Robert Hall

    Robert Hall Subscriber

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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,
     
  6. MattKing

    MattKing Subscriber

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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.
     
  7. Robert Hall

    Robert Hall Subscriber

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    No suggestions with _your_ first name? :wink:
     
  8. MattKing

    MattKing Subscriber

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    Too many "t"s :smile:
     
  9. Ian Grant

    Ian Grant Subscriber

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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 :D 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. Rafal Lukawiecki

    Rafal Lukawiecki Subscriber

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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
     
  11. Ian Grant

    Ian Grant Subscriber

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    You need to make sure the press warms up well, it takes a couple of hours for mine to reach a good even temperature.

    As I said in the previous reply that tissue is quite a low temperature one designed for all papers, at one time there was tissue for RC papers and a the older higher temperature shellac tissue for FB. However as the lower temperature tissue work with all papers and use a synthetic adhesive they were cheaper and far easier to produce.

    I've not dry-mounted a print for over 20 years, but I do remember the very short times needed with the Lion/Hot Press tissue and how much easier it is to use, I've mounted prints with it just using a domestic iron & a sheet of brown paper. I do still have some and will have a go again during the week, I use my press to flatten FB prints.

    Ian
     
  12. George Collier

    George Collier Member

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    In addition to Ian's suggestion about warm up time, I remember that solutions to various adhesion problems may lie in finding the right combination of temperature and time, for the tissue and board you are using. Too high a temp can over heat the board and print, which can give the print time to lose adhesion in some areas after removal from the press. I used to remove the mounted print and immediately place it between two large heavy pieces of flat aluminum, under weight. I had two sets of these plates, and wouldn't remove the print till I had placed another print in the other set of plates.
    I've never seen this edge problem, but it could be related to this. I haven't dry mounted in some time either.
     
  13. richard ide

    richard ide Member

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    It is hard to tell the edge profile from your photo; but is there any possibility of the paper being overwashed? I had this happen once with RC paper that an employee processed. The edge of the paper absorbs water and swells permanently. Try mounting a scrap of paper cut from a processed sheet to test this.
     
  14. Ian Grant

    Ian Grant Subscriber

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    This is a FB paper issue, nothing to do with over washing RC papers. It's exactly what I had happen when I switched to this particular company's tissue. Too hot/too long and it does this, it's getting the balance right.

    With the older shellac tissues there was no problem but then they need temperatures that can cause major problems with RC papers so newer tissues were developed. Get these too hot and they soak into the mounting card, as the card re-adsorbs moisture the ridge becomes aparent.

    Ian
     
  15. Rafal Lukawiecki

    Rafal Lukawiecki Subscriber

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    Thanks everyone. I will be mounting shortly this morning, I have over 20 prints to do and I will try your suggestions. It very much feels to me like too long or too warm, so I will try limiting those parameters, but perhaps I may need to increase the pressure to prevent the corner de-lamination (when bending after cooling) which got me to try longer/hotter settings.

    I really appreciate your wisdom.

    Rafal
     
  16. Robert Hall

    Robert Hall Subscriber

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    Best of luck, let us know how it turns out today.
     
  17. Rafal Lukawiecki

    Rafal Lukawiecki Subscriber

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    I suppose I am late with the summary of how it worked out in the end. Well, I reached an impasse. I can either have no dimpling, but the prints will delaminate when I bend the mount board severely at corners, or they will have good adhesion at the price of some edge-long dimples. I think I made the dimples less visible, but I cannot get rid of them entirely. Looking just now at 28 mounted prints I can see that only 6 have almost no dimpling (the edges ever so slightly come up though), while 22 have dimpling. As I have been making notes on the times in the press for each of those, I can only see that what is common to all of the less dimpled prints is that they all (bar one) delaminated after an initial pressing and had to be returned to the press for extra time and overall they were pressed at a lower temperature for longer.

    I have been cooling each print between two sheets of glass immediately after pressing for a minute or two, then cooling a little more between mountboards, and testing for adhesion by corner bending.

    Maybe I am bending them too much?

    I am, overall, at a loss to make sense out of the whole "experiment". I mounted some 40 prints in total. I started with lower temp (80-90˚C, 175-195F below the top protective mountboard, 100˚C, 215F at the platen) and longer times 3-3.5 min. This has led to less edge-long dimpling but far worse adhesion with frequent delaminations at corners, requiring a print to be returned once or twice back to the press. One print went back 3 times before it passed the "bending" test.

    Then I decided to increase the temperature progressively at the platen to 121˚C (250F), which was giving temperature of about 90-100˚C (195-215F) under the top protective mountboard (4-ply all the time). Trying a sequence of progressively shorter times clearly failed to activate the Unimount Classic tissue evenly at 45 s pressing time. Time of 1 min 5 s seemed to do the trick, with prints adhering well or requiring one more trip to the press for another 1 min, when they always seemed to adhere. Unfortunately, the dimple was back, perhaps not looking quite like a "valley" but more like gently lifting edges.

    I don't know what to try next, but I am keen to try a different tissue to see how it may improve things. I wonder if I can get any ColorMount in Europe, or perhaps I will try one of the HotPress's Archival Grade ones, they are reversible like Seal's BufferMount.

    I have also tried other suggestions made here, that is pressing "upside down" with the print under the mount board, the press had been well prewarmed for over a day, and I have been using pre-dried boards and prints.

    If anyone wishes to make any other suggestions, I would be grateful.

    Rafal
     
  18. Robert Hall

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    So on this bending. I have to ask, exactly how much do you bend your boards? Do you think this will happen to your prints? I am assuming that you do this just to make sure the bond is strong, but I would suppose that if the print is on there, I wouldnt expect it to just fall off.

    I do flex mine about 3 inches across the whole print when cool. If I don't hear a pop, I let it go. I really don't expect them to either fall off or to be flexed as I expect them to sit in a frame for the rest of their life.

    Outside a frame, all sorts of evil can happen to a print. The least of which worry me that someone will bend it over their knee. :smile:

    Cheers,

    R
     
  19. George Collier

    George Collier Member

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    Rafal - You know, I just read your last post, and you are doing something I've never done in the past (or seen done). You use a much thicker protective layer between the platen and the print than I ever have (4 ply). When I was dry mounting, I used only a sheet of dry mount release paper (sold by Seal at the time) between the print and the platen. This is a waxy feeling paper that is smooth and somewhat glossy on both sides, and will not stick to the tissue. With this, you don't have to allow for temp differential. I actually made a large folder of the release paper, the size of the platen.
    I used about 210F for about 25 seconds (3 min + seems very long to me) with good results all the time.
    I also pre-heated (to drive out moisture) both the print and the board).
    Then tacked the tissue to the print.
    While the board was being pre-heated, I trimmed the tissue to the edges of the print with a razor blade.
    Then I tacked the print to the board, then put it in the press.
    This was with MT-5 tissue and fiber paper. You might try release paper instead, without adjusting the temperature.
     
  20. Rafal Lukawiecki

    Rafal Lukawiecki Subscriber

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    George, thanks for your suggestion. I have not tried silicone release paper, but having used a very thin sheet of paper I experienced problems with very uneven heating. I suppose I should try once more with a very short pressing time. Thanks for making this suggestion.
     
  21. jeffreyg

    jeffreyg Subscriber

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    I too use release paper and acid free interleaving paper between the platen. I also turn the sandwich 180 around when 3/4's time has expired. I tack only on three corners. Cool under a metal plate and have not run into your situation. The prints are on FB paper and the mat board is 100% rag. However, I have been shying away from dry mounting and going to archival corners more frequently because if the board is damaged or develops climate stains with our high humidity the print is shot.

    http://www.jeffreyglasser.com/
     
  22. George Collier

    George Collier Member

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    Rafal - If you have experienced uneven heating with a thin protective sheet, maybe your platen is not heating evenly??
     
  23. John Koehrer

    John Koehrer Subscriber

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    Don't the tissues actually bond while they cool down? Try leaving the print between the glass a little longer.
     
  24. Rafal Lukawiecki

    Rafal Lukawiecki Subscriber

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    I owe you an answer how to solve the egde-long dimple problem, even though it has been more than a year since I started this thread.

    As I have attended John Sexton's excellent The Expressive Black and White Print workshop (my experience: http://rafal.net/2012/02/the-expressive-black-and-white-print-workshop-by-john-sexton/), a true gem was meeting his wife, Anne Larsen, who is a perfectionist when it comes to finishing prints, which includes dry-mounting, her primary technique of mounting. Her finish is faultless in every way...

    Anne explained that the edge-long dimple was a problem affecting some papers, notably MGIV, which I use a lot. Perhaps it is to do with the very strong anti-curl features of this pleasantly stiff paper. Incidentally, I think the issue is also related to the size of the print, as at smaller (less than 12") sizes it happens less frequently. Anne's solution is to mount the print normally (see below for her approach), and then:

    • Let the press cool down to about 80?C (ca. 175?F),
    • Insert the already mounted print back into the press for a further 4 min or so, and apply full pressure.
    Please note, that these instructions apply when using traditional tissues, such as Unimount or Colourmount, which adhere when hot. I am not sure, and I have not asked her, what would be the procedure with tissues that bond on cooling down, like Buffermount etc. As a philosophical aside, don't all tissues bond when they cool, difference being the temperature point?

    All of this is in reference to a "normal" mounting procedure, which would be quite different for everyone, I suppose. So as a reference, this is what I observed as her approach, when mounting work using Colourmount tissue:

    • The press (usual, mechanical) is set to a very, very hard level of pressure. There was no way I could even half-close it with my hand between the plattens, when cold.
    • The bottom bed, which usually comprises foam over masonite, was used upside-down, with the foam below, acting as a spring, and the hard, masonite surface was on top, therefore under additional mount boards, which were placed under the mount board, that the print was being mounted to. I realise this contradicts the wisdom from the queen of mounting, Chris Paschke, as written in her handbook. But, it worked.
    • Operating temperature was 93? C (200? F).
    • There were two 4-ply (1.2 mm) boards under the print's own mat board, and so above the masonite.
    • There was only 1 sheet of regular 4-ply mount board above the print and under the platten.
    • She did not pre-dry mount boards (to my surprise, not sure if I could skip this step in Ireland's humid air).
    • Print was pre-dried (and flattened) for 40 s under full pressure.
    • Anne used a "cross" or X tacking pattern.
    • The time in the press was 4 min.
    • Out came perfection.
    As a test, Anne recommended tearing a finished, mounted print, to see if the tissue adhered correctly to the print and the board. She did not feel there was a need to bend prints to check for corner adhesion, if you have tested the process a few times by tearing prints.

    So, there you are. Now I need to try it all on my prints to see if I fix this recurring issue. By the way, there is every chance that I have written down my steps incorrectly, so please test, before relying... Any more feedback would be always very welcome.

    Rafal
     
  25. Rafal Lukawiecki

    Rafal Lukawiecki Subscriber

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    I was dry-mounting today, and I have experienced the same problem. The solution described above has worked, and the edge-long dimple is gone. On another note, I have also moved closer to Anne's dry-mounting process, adding time, and pressure. The results are better, adhesion seems much better, but I still got an odd dimple—now rectified.