Bubbles in Dry Mount

[JBergelin]

Last spring we moved locations....Until then I never had a problem (that I knew about) with dry mounts using my Seal 500.

Since moving we have had problems with bubbles.

For the first time - same press - we have had pieces returned with bubbles or have had bubbles form in house. We pre-dry... use Fusion 4000... and complete the process by cooling under weight. We have used the temp gauge provided by C resent to check the temp. and have tried using a probe. The temp is 170.

Here is where it gets really confusing. In desperation we took pieces to a friend to put in his vacuum press. He has never had problems with bubbles - but one of my posters bubbled in his press. We put it back in the press, it came out looking good so we delivered it --

Then we had a photo that I originally did in the seal 500 using the steps listed above come back. I took it to my friend with the vacuum press -- it looked good coming out of the press so we brought it back to close up --- lo and behold the bubble is back.

Does anyone have any solutions to the bubble problem?

 

[CAframer]

A couple of thoughts ...

(a) You don't mention how large these prints are ... if they are large sometimes adhesion can occur at the perimeter prematurely, trapping air at the center, leading to bubbles ... this can be resolved using the two step process ... put the assembly in the press, create vacuum, then bring up to heat, then leave in place for the usual dwell time.

(b) I find that I need more than 170 for Fusion to melt ... I usually need somewhere around 200.

 

[Framer Jim]

It sounds like the humidity might be to high. Most problems with dry mounting occur because of humidty is to high in the paper or in the board. You might have to put them in the press for a minute or two to get the moisture out of them. Then go ahead and mount them as usual.

What happens with clay-coated papers which is more prone to retain moisture than open-pore papers. In the clay-coated papers, moisture is pushed down towards the mounting tissue but the tissue does not let it pass thru and will cause a lack of adhesion. When re-exposed to the normal environment; it again reabsorbs moisture and the paper again expands which are the bubbles that appear.

 

[Jerry Ervin]

Have you tried using another adhesive product?

I like to use TechMount for regular dry mounting. I save the Fusion 4000 for mounting stuff like cloth.

A vacuum press really helps to pull the air out and that is something a mechanical press just can't do. With a mechanical press, you have to force the air pockets out by applying more pressure.

Have you tried adjusting the clamping pressure on the 500?

 

[Val]

I just recently started using Fusion 400 and had the same problem with bubbling. And they appeared later in the day. I have a press, not a vaccum table. Put it in with more pressure, but still bubbled. Tried cooling under weight. Still bubbled. Was set at 180, I moved it to 200 and like Andrew said, it worked better there.

I think I'll save the Fusion 400 for cloth, as was also mentioned and go back to Colormount/Techmount, since I don't have the vaccum capacity either.

 

[Rick Bergeron - CPF]

Since you have checked temperature calibrations, have you checked the pressure setting for the 500? It is more likely to have changed during a move than the temperature. With your normal mounting thickness in the press, does the arm rest at 45 degrees? Since a vacuum press worked better, that is also an indication of a mechanical pressure issue. We calibrate ours using 3/16" foamcore and add a layer of matboard when mounting to 1/8" foamcore.

Ditto on CAframer (Andrew)'s comment (a). More heat is not always better and can cause premature adhesion around the perimeter.

You didn't say whether you are using separate adhesives or adhesive coated foamcore. 170 will cause bubbles when using any of the Bainbridge adhesive coated foam products with a few exceptions.

 

[Kittyfaces]

I, too, was wondering if maybe your pressure got knocked out of whack.

The other thing I wonder about is: is it possible that the new building your in has more humidity... or maybe you were storing your substrates and adhesives on an interior wall at the old place and maybe now they're up against an exterior wall? Perhaps it's just a matter of predrying longer than you did at your last location.

If you don't already do it the following way, you can predry the item and substrate in an envelope of kraft paper which absorbs the moisture and also dry under weight with kraft paper above and below the piece. I predry "twice": I close the press without locking it for about 10 seconds, lift the press back up to let moisture escape and then I close it again, unlocked, for another 10 seconds to really tap out the last little bit.

 

[DTWDSM]

W had a simular problem a few years ago and changed the pressure, mounting tissue, foamboard, temp, time in the press, and everything else we could think of. We then changed the pad and the problem stopped. The pad can get too hard and wil cause the bubbles.

United has replacemnt pads.

 

[JBergelin]

Thanks for the input

Thanks for the ideas - we ordered a new felt pad from United and different mounting tissues. I will try raising the temp on the bubble we have in house and hope that we can "cure" it.

The comments were most helpful and appreciated.

 

[Jim Miller]

Dry mounting is a touchy process, totally dependent on proper control of time, temperature, moisture, and pressure (TTMP) involved with the mounting. I think a lot of framers misunderstand how important these things are, as most dry mount problems I've seen are not realized until some time later, when the failure is obvious. However, in nearly all cases the failure was caused by some TTMP problem during the mounting process.

After reading through all 9 posts here, I do not recall seeing anything about dwell time -- the amount of time the heated press is clamped on the assembled materials. If you predry properly, have correct press temperature, have proper clamping pressure, and cool under weight, then dwell time is the only remaining factor to check.

I agree that increasing temperature might not help, and could cause damage to some artworks. It would probably be better to increase dwell time, making sure the heat penetrates throughout the entire mount package. If you use a release board instead of release paper, then more dwell time would be required to penetrate that extra board thickness.

Kittyfaces says to predry twice for 10 seconds. I suggest that predrying takes more like 2 or 3 minutes. You can never predry too much, but 20 seconds certainly is not enough time to cook moisture out of the boards, especially if ambient humidity is high.

Whatever your problem is, the good news is that Fusion 4000 is reheatable. That is, you can put it back into the press and reactivate its bonding properties again. Most dry mount tissues will bond only one time. Reheating them would not reactivate their bond, and could actually degrade the original bond.