Block mounting photos on MDF - HELP!

Geofflove · Post by **Geofflove** » Wed 13 Jun, 2007 7:27 pm

I've got some large photos (about 70cm * 40 cm and had a problem mounting them on mdf.....

I first mounted them with 3m spray mount without realising this was
a temp mounting product - they peeled off after a few days....!

The then reapplied 3m photo mount onto the mdf and re mounted the pics. This was more successful but about 5 months later and in this warmer weather bubbles are starting to appear as areas of the photos detatch themselves.....

Is this because there was still some of the old spray mount on the surface or is this common with photo mount.

What do people reccommend? I suspect removing the current photo will damage them so will need to get the reprinted and start again.

If I do it again on fresh photos with photo mount will I be safe of will it happen again?

Are there any better products for block mounting photos in this way?

- of do I need to prepare the mdf first by applying a pva wash or similar.

I know some question the use of MDF at all. The effect I Im trying to get is of the photos mounted ona thick, solid block about 6 cm thick I have achieved this using a sheet of MDF with a softwood 'frame' of about 5cm*5cm wood around the back edge. All edges have been sanded and painted and look great - if I could get the photo

to stay on the block of course....!

If anyone would like to suggest any other materials or approaches to achieve the effect I'd welcome your thoughts.

Thanks

Geoff

Any thoughts?
Thanks

kev@frames · Post by **kev@frames** » Wed 13 Jun, 2007 7:32 pm

PVA ?[/b]

Geofflove · Post by **Geofflove** » Wed 13 Jun, 2007 7:37 pm

I should have made clear.... I'm not a 'professional framer' - don't tell me you didn't guess....!

Therefore I don't have access to presses etc. I therefore need a 'home' solution!

I saw Spray 77 mentioned elsewhere..... anyone think it would work?

Not your average framer · Wed 13 Jun, 2007 7:45 pm

I try to avoid block mounting onto anything these days because of the hassle involved and the tendancy of bowing which has to be overcome. However, if I have to, I block mount onto 12mm MDF and coat the surface of the MDF with two coats of good quality PVA wood glue (not the cheaper and thinner builders PVA). I apply it with a paint roller and allow each coat to fully dry before fixing the art to it in the dry mounting press.

In my experience, IT ALWAYS BOWS and often I have to do something about it. Not my favorite job!

Roboframer · Post by **Roboframer** » Wed 13 Jun, 2007 8:35 pm

I don't & won't do block mounting, but if I did and I did not have a press I'd use PMA - which is basically a big roll of double sided tape.

I used this stuff in a previous life and had a lot of bad experiences, basically you either have equipment that costs a lot of money but makes life easier and does a good job, or you are clever.

Or you can be clever AND have the gear!

foxyframer · Post by **foxyframer** » Wed 13 Jun, 2007 10:29 pm

Geoff

If you are going to take on any job, like Robo suggests, be geared up to the task. One: have the kit - Two: know how to use it.

Many framers will take in work with a remit, then wonder how the hell to do it.

Back in the 70's block prints were all the fashion. Always on chipboard and heatsealed. They always bowed. Total pain. Laminate one side, it will happen.

If you must take on blocks, most framers don't want to know, it's MDF smoothed to a babies bottom finish or that tiny speck will show up like a beacon, using a cold mounting roller.

Personally I avoid blocks nowadays, given there are so many other 'smart and simple' ways of presenting photos

Don't use spray mount for anything!

michelle · Post by **michelle** » Thu 14 Jun, 2007 3:36 pm

I have blocked mounted some photos for myself onto 6mm mdf, using the Hot press (laminated also) . How long can I expect them to last, and what is it that makes them bow? at this moment in time I can't imagine them going anywhere but I have only had them made a couple of months.
thanks M

Merlin · Post by **Merlin** » Thu 14 Jun, 2007 4:15 pm

Why does MDF or Laminated pictures bow? One answer (and I am sure there are a few others) given to me a long while ago by a master cabinet maker is the Bi-metalic strip principle.
Ideally MDF if used for cold/wet mounting needs to be PVA'd on both sides first and allowed to dry thoroughly. If only one side is PVA'd then the fibres in the MDF are effectively bound (glued) together and the glue will seep a short way into the material. The other side is free.
If the material needs to expand or contract for whatever reason then the side that has not been glued or locked will be free to move, the glued side will not. It might only be a few thousands of a millimetre of movement but even over a small distance it will all add up.
The cabinet maker always used to Shellac both sides of his work to bind the fibres, before any finishing touches were used.
Seems quite logical to me, but then again physics was not a particularly strong point of mine.