Bubbling!

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invernessframer
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Bubbling!

Post by invernessframer »

Hello,

I'm looking for some advice on which self-adhesive boards to use for cold mounting. The ones I've been using so far are the value self adhesive ones from Lion, but I've had a couple of things bubbling. We're fairly new and still finding our way with suppliers so I was wondering if anyone had an recommendations? And also how to minimise the risk of the dreaded bubbling in the future, I use a roller but maybe need to do it for longer? And in terms of fixing the bubbles is piercing a tiny hole in one and re-rolling the best thing to do?

Thanks!
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Re: Bubbling!

Post by Justintime »

Give Steve Goodall a call at Wessex, he's the expert on hot/cold mounting/laminating and materials. I think he's based at Oldham 0161 6812959
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prospero
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Re: Bubbling!

Post by prospero »

Self-adhesive boards use a pressure sensitive adhesive. The key word here is PRESSURE. With a hand roller you are never
going to get even pressure over the whole surface and so some localised spots are not going to be bonded properly. These are the
areas that will bubble. This board is quick and convenient, but far from reliable.
A Jetmounter is the thing to use but that means spending ££££££s. Even then I wouldn't totally trust it.

The problem is, once a bubble forms it's area is slightly greater than the spot it raised from and trying to flatten it generally results
in a half-moon crease. Even worse, where it has bonded it will have bonded hard, making the print impossible to remove. :|
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Rainbow
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Re: Bubbling!

Post by Rainbow »

Have a look at this Larson Juhl video which shows a "foolproof" (if there is such a thing) way to lay down prints/photographs on to self-adhesive board.

https://www.youtube.com/watch?v=aI9YvtnVEj0

I've seen another video which I can't now find, which started at a corner with a large postal tube and gradually peeled back the protective sheet as they rolled it out from the corner.
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Re: Bubbling!

Post by Not your average framer »

Bubbling is something that easily happens with self adhesive boards, particularly in hot weather, like we are experiences at the moment. I have also read that self adhesive board is not a gool choice for use on larger areas requiring to be bonded to a substrate. Self adhesive materials are often refered to as pressure sensitive, which is a good thing to rememer. The strength of the resulting bond depends at lot on the pressure applied to make that bond.

Not enough pressure applied to make that bond and the long term bond may not be particularly reliable. Roller machines which apply that pressure, have their limits in how effective they will be as the area to be bonded increases. The overall pressure the machine can apply is still the same, but that pressure is being applied over a larger area, some the pressure available at any one point is limited by the fact that that same amount of pressure is being distributed over a larger area.

Another fact is that self adhesives are not intended to penetrate into the surface of the materials which they are bonding to, but the only bond to the surface, but external means. Unfortunately, the chemical components which make self adhesives sticky are volatile ingredients which do not remain sticky for ever. They have a shelf life, which determines how long that they can be stored for before a reliable and effective bond is no longer a viable possibility and they also have a service life, which is how long that bond will actually continue to been effective after the initial bond has been made.

Sorry to spell this out, but self adhesive strengths of bond and the useful life of this degree of bond are limited. There is no such thing as a permanent bond with most self adhesives, they all fail eventually, it's just a matter of time.
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Re: Bubbling!

Post by invernessframer »

Thanks so much for the replies.

I'm curious about what you guys tend to use instead of self adhesive boards for flattening/smoothing things out? Always heat/dry mounting? What if you're concerned about potential damage to a piece of work under heat, would you just advise the customer not to stick it down at all and live with the creases?

The most recent thing I cold mounted and it bubbled was a fairly large poster printed on fairly thin brown/recycled type paper. It was getting a mount and had been rolled up for a long time so I thought sticking it down would be best to avoid gaps along the mount aperture, what would you have done? We have a small heat press but haven't actually gotten it up and running yet!
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Re: Bubbling!

Post by Rainbow »

I'd have put it down on a flat mountboard, covered it with another mountboard, put loads of heavy books evenly across the surface and left it for several days.

If that didn't fully flatten it, I might have tried reverse rolling with a very large tube - but only because you've said it's thin paper, I'd be hesitant about doing reverse rolling with thick paper in case it cracked. Here's a video showing how to do a reverse roll:




There's this other one where the framer wraps the poster round a rolling tube, but it would be safer to use some kraft paper or similar for protection. I've used cellophane in the past, or you could use tissue paper.


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Re: Bubbling!

Post by Not your average framer »

In a hot humidy climate like we are experiencing at this time in august, the thin brown paper is going to absorb moisture from the air and try to expand and I will want to expand quite a lot. The self adhesive board is not going to be able to continue sticky to the now quite moist paper and the expanding forces within the paper are going to produce forces that are going to be irresistable. The paper is going to expand and cockle, resulting in the bubbles that you are complaining about.

The result is largely unavoidable, If you are going to use self adhesive board to mount such a large piece of paper. Mounting anything as large as a poster using self adhesive board is unfortunately asking for trouble. The larger the piece of paper, the larger the increase in the size of the piece of paper will be with the effects of humidity. I have read that mounting anything over 12" x 16" onto self adhesive board is not a wise move, personally I would not willingly go this far, in fact I would probably say 10" x 10" is probably safer.

The framing workshop, were I was trained liked to use self adhesive boards in conjunction with a heated press, which made sure that the artwork stayed put while it was being bonded in the press, but also melted the acrylic adhesive rendering the adhesive no longer self adhesive and instead the acryic part of the adhesive became a heat activated dry mounting adhesive. As far as I know this was extremely successful and did not result in any future problems. They even used this method for mounting cross stitches, I was not a big fan of doing it this way, but it did work!
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Re: Bubbling!

Post by Richard Photofusion »

I've mounted thousands of prints using our JM44. We prep our own selfadhesive board, using adhesive from Hotpress. Papers ranging from 34gsm Kozo up to 340gsm alpha cellulose.
Only times we've had bubbling have been down to either user error (normally pressure too low/uneven) or dodgy rolls of adhesive (all manufacturers I've used have produced Friday afternoon rolls), with my current preference being from Hotpress. Fortunately, we coat the substrate first, so get to see if there are any issues with the adhesive, before it meets the print, and we generally only mount that which we've printed. It is a pita to remove dodgy adhesive from an 8' sheet of DiBond.

Where humidity changes are a real pain is with lightweight mounting boards (Kapamount, or 3mm Forex), when the result is not framed. Going from a cool dry workshop, to a hot and humid gallery can cause bowing, but where this is the case, we mount the same paper (unprinted) to the reverse of the substrate, creating a ply material that has the same expansion / contraction on both faces.
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Re: Bubbling!

Post by Not your average framer »

It's a lot more basic at my end. I don't do the Dibond mounting at all and I mostly dry mount onto bought in sheets of Dry mount board. I also have a hot press manual roller machine, which I can also use with self adhesinve board, or self adhesive optically clear film. Dry mounting and self adhesive mounting are not necessarily my first choice, because I prefer to use fully reversible techniques when I can, but that is not always the most appropriate solutionn.

Cheap flimsy posters,or posters which have been crunched in the suitcase, on the way back from being on holiday, just look aweful if you don't do something about it. It's also nice to be able to heatseal some really flimsy posters with a matt heatseal film, where a mount is not wanted and I don't want the poster getting stuck to the glass. I'm often quite surprised how good some of these posters look after having been framed for very many years.
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