I understand that there are a couple of different kinds of ATG Gun tape. Can someone explain the two types and their various uses? I have heard them called agressive and non-agressive, but I am curious as to what the 3M code number is and what their uses are. Thanks in advance for any information.
KINDS OF ATG TAPE
- Thread starter Jason
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preservator
SGF, Supreme Grumble Framer
3M ATG 969 is thicker than normal ATG and is very strong. It has excellent
adhesive properties and is also quite cohesive, which makes it somewhat easier to handle, but it is so stong that it must be handled carefully, to ensure
that it does not stick to unintended surfaces.
Hugh
adhesive properties and is also quite cohesive, which makes it somewhat easier to handle, but it is so stong that it must be handled carefully, to ensure
that it does not stick to unintended surfaces.
Hugh
ATG tape is generally a carrier-less pressure sensitive adhesive. That is, all adhesive, no tape. It is handy for temporary bonding of matting layers and it works OK for dustcovers, and that's about as far as it goes. And for those purposes, most ATG products work similarly.
3M #924 is probably what one might call the industry standard. 3M #969 is, as Mr. Phibbs pointed out, much more aggressive. 3M #908 "Gold ATG" is my personal favorite. It is acid free and more aggressive than #924, but not as aggressive or as thick as #969. 3M is most popular, but other makers have similar products by their own numbering system.
If you are considering ATG for any application where it would be under stress of any kind -- such as holding any amount of weight against gravity -- I suggest you consider something else, because ATG certainly is not a suitable adhesive for that. Being relatively thick and gummy, it will flow and fail under stress.
A lot of framers try to use ATG to mount three-dimensional objects, which creates an undependable mount. Here's an amusing story: In a class on object mounting, sponsored by a distributor who invited all their local customers, one framer declared that he'd been using ATG for years, to mount lightweight CDs and their cases, and had never had a failure come back. Another framer - obviously a competitor - said he repaired those failed mounts for customers who didn't want to go back for more of his poor workmanship.
3M #924 is probably what one might call the industry standard. 3M #969 is, as Mr. Phibbs pointed out, much more aggressive. 3M #908 "Gold ATG" is my personal favorite. It is acid free and more aggressive than #924, but not as aggressive or as thick as #969. 3M is most popular, but other makers have similar products by their own numbering system.
If you are considering ATG for any application where it would be under stress of any kind -- such as holding any amount of weight against gravity -- I suggest you consider something else, because ATG certainly is not a suitable adhesive for that. Being relatively thick and gummy, it will flow and fail under stress.
A lot of framers try to use ATG to mount three-dimensional objects, which creates an undependable mount. Here's an amusing story: In a class on object mounting, sponsored by a distributor who invited all their local customers, one framer declared that he'd been using ATG for years, to mount lightweight CDs and their cases, and had never had a failure come back. Another framer - obviously a competitor - said he repaired those failed mounts for customers who didn't want to go back for more of his poor workmanship.
SusanG
SGF, Supreme Grumble Framer
It sounds like you don't use ATG tape to bond your mats. What do you use to put your mats together, Jim?
Susan
Whispering Woods Gallery
Susan
Whispering Woods Gallery
The key thing is, don't use ATG alone for this purpose, particularly if you cut your double mats using the method with the undermat being slightly recessed from the outer edges of the face mat. Combine ATG with dots of a white glue such as Cornerweld or whatever you commonly use. It is the glue which will do the holding long-term, with the ATG serving to keep everything lined up while the glue dries. If you don't use any glue, eventually the ATG- which, as Jim pointed out, never hardens- will allow the undermat to slip down due to shear created by gravity. This results in the phenomenon often called "Mat Creep", where the undermat is too wide at the top and too narrow at the bottom.
We hate this creep.
Rick
P.S.: This rule applies to installation of shadow box spacers and the like also.
We hate this creep.Rick
P.S.: This rule applies to installation of shadow box spacers and the like also.
Val
PFG, Picture Framing God
"Mat Creep"....related to "The Flumb Pervert"?
preservator
SGF, Supreme Grumble Framer
Pressure-sensitive adhesives are sensitive to pressure. That means that if
they are used to hold heavy items, objects or mats, those items will move,
eventually. When things have to hold, a water-based adhesive is a safer bet.
Hugh
they are used to hold heavy items, objects or mats, those items will move,
eventually. When things have to hold, a water-based adhesive is a safer bet.
Hugh
Dancinbaer
SGF, Supreme Grumble Framer
The key thing is, don't use ATG alone for this purpose, particularly if you cut your double mats using the method with the undermat being slightly recessed from the outer edges of the face mat. Combine ATG with dots of a white glue such as Cornerweld or whatever you commonly use. It is the glue which will do the holding long-term, with the ATG serving to keep everything lined up while the glue dries. If you don't use any glue, eventually the ATG- which, as Jim pointed out, never hardens- will allow the undermat to slip down due to shear created by gravity. This results in the phenomenon often called "Mat Creep", where the undermat is too wide at the top and too narrow at the bottom.
Rick
P.S.: This rule applies to installation of shadow box spacers and the like also.
When doing shadow boxes I've always used a combination of ATG and adhesive for mounting certain objects. But this is the first I've heard of using both between mats. Now I'm very curious and wondering about all the framing I've done over the past 4-1/2 years. Are the mats starting to "creep"? While visiting other framers I've watched them just use ATG alone between mats. Maybe Mike can do a poll on this subject.
Isn't the pressure of the glass on the mats on the backing board enough pressure to prevent "creeping"?
Mat Creep
As Rick described, I use ATG for temporary positioning, and water based paste for long term bonding.
One issue is that, as Hugh pointed out, pressure sensitive adhesives rely on PRESSURE to activate the bond. That's easy enough when you're bonding a thin, flexible item (such as tape) to a solid board -- just burnish it to activate the bond. Have you noticed how ATG seems to stick best to the board it was applied to? That's because those little rubber rollers on the applicator gun apply pressure to activate the bond on that surface as the ATG is applied.
But how do you apply pressure on the ATG between two boards? Impact (mat smacking) is probably the easiest way, but putting the assembly under weight overnight or in a vacuum press for a few seconds works, too.
Trouble is, many framers (most framers?) do not apply enough pressure to properly activate the bond between mats, which assures eventual failure of the bond. I guess a lot of them do not realize that ATG works only after pressure is applied.
"Mat Creep", evidenced by unequal margins of accent mats, can be seen on multiple mats only a few years old. It looks like sloppy mat assembly, but in most cases the accent mat margins were perfectly spaced originally, and shifted over time.
What happens is that when environmental changes cause expansion/contraction cycles, the top mat, which is in direct contact with the glass, expands & contracts more and faster than the under-mats, which are insulated from the glass by the 4-ply top mat. Paper is a very good insulator.
As the expansion/contraction differs among the mat layers, their surfaces slowly rub, trying to shear the adhesive bonding them together. If it is ATG or other pressure sensitive adhesive, it will flow and fail, but perhaps only in certain places. For example, if the top margin's strip of ATG fails and it shifts on expansion, and the left side's ATG strip fails and it shifts on contraction, then the under-mat would change its position relative to the top mat, making the accent mat margins unequal.
As Rick described, I use ATG for temporary positioning, and water based paste for long term bonding.
One issue is that, as Hugh pointed out, pressure sensitive adhesives rely on PRESSURE to activate the bond. That's easy enough when you're bonding a thin, flexible item (such as tape) to a solid board -- just burnish it to activate the bond. Have you noticed how ATG seems to stick best to the board it was applied to? That's because those little rubber rollers on the applicator gun apply pressure to activate the bond on that surface as the ATG is applied.
But how do you apply pressure on the ATG between two boards? Impact (mat smacking) is probably the easiest way, but putting the assembly under weight overnight or in a vacuum press for a few seconds works, too.
Trouble is, many framers (most framers?) do not apply enough pressure to properly activate the bond between mats, which assures eventual failure of the bond. I guess a lot of them do not realize that ATG works only after pressure is applied.
"Mat Creep", evidenced by unequal margins of accent mats, can be seen on multiple mats only a few years old. It looks like sloppy mat assembly, but in most cases the accent mat margins were perfectly spaced originally, and shifted over time.
What happens is that when environmental changes cause expansion/contraction cycles, the top mat, which is in direct contact with the glass, expands & contracts more and faster than the under-mats, which are insulated from the glass by the 4-ply top mat. Paper is a very good insulator.
As the expansion/contraction differs among the mat layers, their surfaces slowly rub, trying to shear the adhesive bonding them together. If it is ATG or other pressure sensitive adhesive, it will flow and fail, but perhaps only in certain places. For example, if the top margin's strip of ATG fails and it shifts on expansion, and the left side's ATG strip fails and it shifts on contraction, then the under-mat would change its position relative to the top mat, making the accent mat margins unequal.
SusanG
SGF, Supreme Grumble Framer
OK, I'm guilty! I use ATG tape to join my mats together. However...Every mat that I cut goes in the cold vacuum press for a minute or so and gets squished together. After that point they are very difficult to separate. I do have a Wizard so my second and third mats are the same dimension. I'm curious to know if many of you are seeing jobs come back with "mat creep?" I have never gotten any back from the olden days before the CMC when the second and third mats were smaller but I think from day one, which is twenty years in January 
I have been putting them in the vacuum press.
Susan
I have been putting them in the vacuum press.Susan
CAframer
SGF, Supreme Grumble Framer
Not taking anything away from the importance of preventing mat creep ... and yes we always use PVA dots in addition to ATG ... but but how many clients actually notice mat creep? ... not many I think based on the number of cases I see when reframing old artwork ... I often point out the problem, along with other issues (acid burn etc) and use the opportunity to explain the difference a quality framer brings to the work ... invariably they say something along the lines of "Gosh you're right ... I never noticed". And that applies not only to the mat creep!
There are numerous other situations where clients don't see the issues we do ... eg. the "glare" from Melinex encapsulations or overlays.
Framerguy
PFG, Picture Framing God
Susan,
I have had no returns either in almost 19 years of framing and I do basically what you have done through the years. I can't account for any that were taken to another shop for repair but I had a loyal customer base when I was in business and I would hope that any problem like this would be brought to my attention. They all knew that I guaranteed my work, period.
I think to say that mats that are ATG'ed together "will suffer mat creep" is a bit of an overstatement. Sure, with the addition of any PVA adhesive to the mat package you should experience no mat creeping or displacement as most of those adhesives don't creep. But I would speculate that the use of ATG only to hold multiple mats together would only offer a possibility of them creeping over time, not a guaranteed "gonna happen".
Denny, I wouldn't get too upset or wired about what you did in the past unless you know beyond a shadow of a doubt that your procedure for ATG'ing mats together didn't stand a chance of lasting very long (like many years) or you are having many comebacks with mat slippage as a problem. I have done them both ways and both ways seem to work as long as you do them properly.
That has been my experience and is my opinion and you can do what you feel most comfortable doing.
I have had no returns either in almost 19 years of framing and I do basically what you have done through the years. I can't account for any that were taken to another shop for repair but I had a loyal customer base when I was in business and I would hope that any problem like this would be brought to my attention. They all knew that I guaranteed my work, period.
I think to say that mats that are ATG'ed together "will suffer mat creep" is a bit of an overstatement. Sure, with the addition of any PVA adhesive to the mat package you should experience no mat creeping or displacement as most of those adhesives don't creep. But I would speculate that the use of ATG only to hold multiple mats together would only offer a possibility of them creeping over time, not a guaranteed "gonna happen".
Denny, I wouldn't get too upset or wired about what you did in the past unless you know beyond a shadow of a doubt that your procedure for ATG'ing mats together didn't stand a chance of lasting very long (like many years) or you are having many comebacks with mat slippage as a problem. I have done them both ways and both ways seem to work as long as you do them properly.
That has been my experience and is my opinion and you can do what you feel most comfortable doing.
High-compression framing?
Nope. Frame fitting should not be tight enough to restrict expansion/contraction or shifting of the contents within the usual 1/8" frame allowance.
Also, typical fitting couldn't possibly impose enough pressure to properly activate the bond.
Also, board thicknesses swell or shrink with changes of humidity, which may constantly change the tightness of the fitting.
Nope. Frame fitting should not be tight enough to restrict expansion/contraction or shifting of the contents within the usual 1/8" frame allowance.
Also, typical fitting couldn't possibly impose enough pressure to properly activate the bond.
Also, board thicknesses swell or shrink with changes of humidity, which may constantly change the tightness of the fitting.
Good point, Tom.
Yes, Tom, you are right. And isn't that possibility enough reason to take such an easy precaution?
Good Heavens, I agree. If framers obsessed about every little thing we once did that we now know better than to do, we'd be crazy. Come to think of it...:icon9: that theory could explain a lot about framing and framers, eh?
It is true, our customers do not usually look as closely at our work as we do. Most consumers might never see "mat creep", and might not think it's a problem if they do.
On the other hand, framing consists of a bunch of small tasks, using various methods and materials that would not individually determine the quality of the total assembly. But every one of those methods and materials contributes something to the whole -- or not. A little improvement here and a little improvement there, and before you know it, the difference shows.
Yes, Tom, you are right. And isn't that possibility enough reason to take such an easy precaution?
Good Heavens, I agree. If framers obsessed about every little thing we once did that we now know better than to do, we'd be crazy. Come to think of it...:icon9: that theory could explain a lot about framing and framers, eh?
It is true, our customers do not usually look as closely at our work as we do. Most consumers might never see "mat creep", and might not think it's a problem if they do.
On the other hand, framing consists of a bunch of small tasks, using various methods and materials that would not individually determine the quality of the total assembly. But every one of those methods and materials contributes something to the whole -- or not. A little improvement here and a little improvement there, and before you know it, the difference shows.
Yet again the question wasn't, "how do you build a clock?"
I swear some of this is made up out of thin air. I guess there are framers out there who are gluing mats and using atg but to date I've never opened a single package where they have. At the same time I've never seen Mat Creep. Surely he isn't a creep. Maybe it's spelled Crêpe. Furthermore I'd consider old agt on mats as "permanent" as pen striping on an old Buick (which is also taped). It might not be an ideal solution in the world of "But Maybe" but in the real world they are pretty dang reliable.
I swear some of this is made up out of thin air. I guess there are framers out there who are gluing mats and using atg but to date I've never opened a single package where they have. At the same time I've never seen Mat Creep. Surely he isn't a creep. Maybe it's spelled Crêpe. Furthermore I'd consider old agt on mats as "permanent" as pen striping on an old Buick (which is also taped). It might not be an ideal solution in the world of "But Maybe" but in the real world they are pretty dang reliable.
Framing Goddess
SGF, Supreme Grumble Framer
I must say I understand Mat Creep in theory, but in 25 full-time years of disassembling and reassembling all kinds of framing nightmares, I have yet to see an instance of this.
I am sure it happens, but I have yet to see it firsthand.
I have see ATG fail on other things, such as 3-D pieces in a shadowbox.
Edie the FWIW goddess
I am sure it happens, but I have yet to see it firsthand.
I have see ATG fail on other things, such as 3-D pieces in a shadowbox.
Edie the FWIW goddess
If you want to see mat creep, take a look at the matted, framed art prints in almost any hotel. It is possible that a few of their accent-mat margins were out of position originally, but after a few years, I'd guess 20% of them are visibly out of position -- sometimes by as much as 1/8".
Just out of curiosity, why does mat creeps mysteriously stop? If a cmc cut the outside then the mats would creep to the bottom of the frame equally and still look right wouldn’t they? If the inner mat were smaller than the outer then you wouldn’t have to “look” for the mat creep. The absent mat at the bottom and the 2” reveal at the top would give it away. Since I haven’t seen this and the mats are creeping, what phenomenon is causing them to just stop after 1/8”?
Before CMCs starting coming in Cracker Jack boxes, framers routinely cut the blank for the bottom mat 1/4" smaller that the top one. If the bottom mat started to head south, it would bottom out about 1/8" later.
I will admit, now that I no longer even pretend to be a picture framer, that I rarely supplemented the ATG attaching multiple mats with glue, but it sounds like good insurance that costs almost nothing in time and materials.
BTW, I just started routinely seaming my glass after 23 years of framing. You CAN teach an old dog new tricks, if the old dog is open-minded and paying attention.
I will admit, now that I no longer even pretend to be a picture framer, that I rarely supplemented the ATG attaching multiple mats with glue, but it sounds like good insurance that costs almost nothing in time and materials.
BTW, I just started routinely seaming my glass after 23 years of framing. You CAN teach an old dog new tricks, if the old dog is open-minded and paying attention.
printmaker
CGF II, Certified Grumble Framer Level 2
Although we've all seen this phenomenon, and we've all seen multiple mats which separated and lost their bond over time, I have to agree here with Framerguy.
We've had the opportunity to reframe some of my own pieces for customers after 25+ years. I've never seen any indication of mat creep with these pieces...
We always try to store matted works flat, under some pressure, prior to final assembly. I would say the longer and more pressure, the better...
Further, every once in a great while, we've had to separate mats for one reason or another. More often than not, mats which have been "properly pressed" for more than 24 hours cannot be separated, no matter how carefully, without tearing the surface papers - the ATG holds very aggressively.
I certainly won't argue the point, and I realize that most framers may not have the opportunity to apply suitable pressure to mulitple mats prior to assembly, but it's been our observation that doing so makes the ATG bond both (seemingly) permanent and inflexible.
Having said all that, I will start to keep a sharp eye out for this problem as, for about 30 years now, we've only used ATG on our multiple mats (and we rarely, if ever, cut single mats).
Framerguy
PFG, Picture Framing God
All the IF's and THEN ................
Making mats bond for the long term is much like many of the other procedures we do in framing and depend on a couple of "if's" to achieve the "then". We have no way of knowing whether all of the steps are routinely followed and which ones were omitted to cause a faulty bond.
Any of these steps omitted could cause the bond to fail. Economy ATG is OK for the budget but it may not have the permanent holding power that you desire for suspending something like an undersized second mat in place. Trying to scrimp could sacrifice a good bond to the amount of ATG you apply to the mats. And placing casual pressure on any ATG bond will not necessarily activate a bond. I have not used a mat smacker but I do put over 10 psi of pressure on the mats for enough time to bond them to the point where, if I notice the bottom mat not lined up correctly, pulling them apart will usually pull the surface paper off of the back mat. If the ATG peels off easily or the mats come apart with ease I would speculate that you are not getting a good bond.
These are my own personal observations and don't reflect on any standard that we follow.
Making mats bond for the long term is much like many of the other procedures we do in framing and depend on a couple of "if's" to achieve the "then". We have no way of knowing whether all of the steps are routinely followed and which ones were omitted to cause a faulty bond.
- If you use a good quality ATG tape that hasn't been laying on a shelf in a case for the last six months
- If you use full strips along each side of the matboards that are being bonded
- If you apply enough pressure to the bond all around
- And if you leave the pressure on long enough for bonding to take place
Any of these steps omitted could cause the bond to fail. Economy ATG is OK for the budget but it may not have the permanent holding power that you desire for suspending something like an undersized second mat in place. Trying to scrimp could sacrifice a good bond to the amount of ATG you apply to the mats. And placing casual pressure on any ATG bond will not necessarily activate a bond. I have not used a mat smacker but I do put over 10 psi of pressure on the mats for enough time to bond them to the point where, if I notice the bottom mat not lined up correctly, pulling them apart will usually pull the surface paper off of the back mat. If the ATG peels off easily or the mats come apart with ease I would speculate that you are not getting a good bond.
These are my own personal observations and don't reflect on any standard that we follow.
I'm surprised that one could be in framing for a long period of time and not see mat creep. It's pretty common here in the Texas heat. Yes, we do have air conditioners but when frugal people go on vacations etc. and leave the air off, well......