Glue for aluminum in ribbons

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The most difficult thing for the DIY crowed to deal with in making/ repairing ribbons is the adhesive.

Many use a spray adhesive like 3M super 77. It sprays evenly, is easy to use, and it seems to damp the foil/mylar combination well.
However this adhesive will dry out in time. environment will determine how fast this happens. And its mechanical properties change wich can change the damping effect.

A better adhesive is good old "contact cement". NOT "rubber cement". Contact cement such as...
16 Oz DAP Weldwood Contact Cement | HD Supply

This adhesive is very strong and will hold its properties for many years.

BTW the spray versions of contact adhesives will spray a thick gloppy uneven coating thats really not suitable for this application.

In the end its the thickness and the evenness of the adhesive that is tricky. Too thick and you will suck the life out of the ribbon.

Contact cement is a thick liquid. I have found two ways to apply it to a good result.

1- thinn it with acetone and spray it on or even roll it on .

2- dont thinn it at all and just roll it on.

Over the years I have come to find that rolling it on (as crude as it sounds) is just as good as thinning and spraying. It doesnt always look like it should be good BUT I hear and measure no difference between the two if done well.

So heres the tricks to rolling a nice even thinn layer of CS>

1- use mini foam rollers like these...

Redtree 4in Mini Paint Foam Roller 2-Pack

these are firm, small cell foam rollers

2- pour small amount of contact cement out on a flat surface and work the roller back and forth over it until roller evenly coated.
3- on a clean flat surface ( I use printer paper) press roller firmly down and roll off excess adhesive. Do this (2-3) until you can get a smooth thin film of adhesive rolling off.
4- now you can coat the foil and the mylar. 1 coat is enough. These should be very thin but even coats. The roller will not be saturated with adhesive as if you were painting. It should be just enough adhesive so roller is not "wet" but it will cover evenly.

5- put 1 coat on foil and 1 coat on mylar. Wait until both surfaces are tacky sticky but not wet. Then press the foil and mylar together. Move around and apply even firm pressure to get good contact.


In the end the application of the adhesive is one of the biggest issues with ribbon making, and more sophisticated method are necessary to get the highest level of performance. However I have found that when the above crude method is done well it easily achieves 90% of that perf and it will last for decades.

Getting good with the roller just takes practice
 
I am in the process of refurbishing/rewiring some Magnepan speakers. I find the instructions from Magnepan a bit confusing. The advice the 3M Super 77 on the Mylar only, press the wire in place and then apply a coating of 3M 30NF on top of the wire or foil conductor. Contact adhesive use to go on both surfaces…
 
I to only use the Dap weldwood,get at WM 1 can $7....Never Use the 3m77
wast of money an never last....my be that's what Magnepan wonts...
The Dap contact cement...work great...but i never use the 3m3onf....Only the
Peter Gun fix....spray pant the dryers in the pant work great to dry the Dap out ...I got 5 years on panels there like the day I did the work...but by all means...I know you can make the Magnepan way work....or you can do it over..good luck
 
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yea I am surprised Maggie recomends the 3M77. In fact I am also a bit surprised they use the 30NF "green" contact adhesive.

I have found the 30NF to be less consistent AND a bit less durable than standard contact cement.

I have been doing indoor and outdoor environmental testing for decades now on many adhesives/tapes/foams. I can tell you this, standard contact adhesive is great stuff. I was looking at a planer woofer proto the other day thats been on the shelf in an unheated shed for about 10 years. The contact cement used on this is still tough and pliable as the day it first dried.
 
No it doesn't matter. The magnet polarity of the 2 outside magnet rows are the same so no matter how you install it will be ok.

Pay attention however to the shim washers (if any) used to space the magnet assembly. These should be put back in same places.
 
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BTW I think I forgot to tell ya, where the aluminum traces actually connect to the brass contacts. Its best if the aluminum trace right at that spot is not glued to the mylar.

This way the brass parts can get a good contact to the traces on both sides, AND there is no glue in there wich can over time cause a loose connection.
 
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