C-prints on acrylic facemount

[markrause]

Hi, I wonder if someone can help me with a problem I have with c-print facemounted on acrylic. After a few weeks, 50% of the pictures I received developed some magenta spots between the picture and the acrylic. It seems to be the result of some sort of chemical reaction between the photo and the adhesive used in the facemount process. I do the print in a photo lab and then send it for a different third party to facemount on the acrylic.  He states that he never had any problems with c-prints that were made in the US that he mounted on acrylic, only c-prints made here in Brazil. He speculates that here,  the photolab may reuse the chemicals or even leave some on the photo during the develop process. But the funny thing is that it only happens with some photos, not all.

I have attached some photos of the spots.
https://www.dropbox.com/s/l3mnctzrs59fxvq/Foto39.jpg?dl=0
https://www.dropbox.com/s/bsari0j2xrj1x0n/Foto46.jpg?dl=0

So, have anyone encountered this problem before? Is there any way to avoid it?

Thanks

[mearussi]

The problem with C prints is that being a chemical process the quality is dependent on how consciousness the owner is about maintaining his chemistry. To cut costs it's an easy temptation not to change the chemistry as often as it should be, especially the fixer, so any number of chemical stains can easily crop up later.

If you have any way of switching to inkjet prints that should eliminate your problem.

[Wayne Fox]

There should be no issues with C prints, and in fact inkjet prints bring in their own challenges as it can stress the delicate bond between the Inkjet receptor layer and the paper.

We have face mounted thousands of C prints and inkjet prints and never seen the issue you describe.

As far a chemical contamination, hard to say, but some printers use a wash system, others use a stabilizer system. The fact that they are magenta could indicate the stablizer tanks of the processor have too much bleach carryover which is somehow reacting to the adhesive (absolute wild guess on that one). But as was mentioned, if you are having problems with them, the lab that printed them needs to address this. 

Sorry not much help.  Not sure of the adhesive being used, the actual paper and finish being used (fuji, kodak, glossy, ultra glossy, etc).

[markrause]

Thanks for the inputs. I use Kodak Endura Metallic paper, and is is printed in one of the few remaining working Durst Lambda here in Brazil. Not sure what kind or brand of adhesive is used for the facemount process. I use this paper and so far I am reluctant to move away from it, as inkjets prints using a paper that could give the same look (such as Moab Slickrock Metallic Pearl and likes) achieve a similar, but not quite the same look. Unfortunately I don't control neither the printing or mounting process, so unless the problem is something very specific that i could point, would be hard to deal with. And what puzzles me is that only some of the pictures show that, and only after a few weeks. I was hoping someone would suggest something like a Hahnemuhle Protective Spray or some easy solution, but I guess i was being to optimist.

[Wayne Fox]

Kodak Metallic face mounts very cleanly and is one of the easier materials to face mount. 

I would chat with the lab and show them the problem.  I’m not sure if the Lambda is a washless process using stabilizer or uses a water wash, but if it’s washless there could be a small amount of residue being left.  Have you shown the results to the lab that printed them?
 
I guess I”m puzzled why you are using two different services for this, there a many labs that offer printing and acrylic facemounting of Kodak Metallic paper.

[BrianBeauban]

There should be no chemical reaction between the print and adhesive,  providing they used a pressure sensitive (solvent or aqueous acrylic adhesive). If they used something else, like diasec (sp?) which is liquid then it could be possible, but no likely. I had an issue years ago where heat could reactivate a dye layer in c-prints produced on the lambda (or lightjet). There should not have been any heat involved with this process (mounting to acrylic). The only way to tell what is going on is to pull it apart and verify that the color is in/on the print and not between the adhesive and acrylic. Then, I would suggest having prints from a different lab sent to the first one for mounting and see if the same thing happens. This is an elimination process where you change one variable to see which one causes the problem. If it still happens then you look at changing either the adhesive or acrylic. If it does not reoccur then you'll know. Either way it's an expensive test. Anything else is pure speculation.