Testing Paper Bag Label Adhesion

Update 1-16-2019 At the bottom of this page is a new method that works well.

A friend of mine owns a grist mill, I want to sell some of his products in my country store. He’s having some trouble with the labeling process. He’s using a nice heavy white paper bag, but he has a number of products; and getting the bags printed requires a large order of each label. That cost is prohibitive.

So he had some adhesive back labels printed. They each have a liner that must be removed, but the biggest problem is that the adhesive doesn’t hold in cool weather. I also think he said that the cost of each label is high. I was sure that a printed paper label was the way to go, and told him I would try to think of a better process.

I thought of several mechanical processes, but as usual, further contemplation ended up at a very simple process. That of course will leave me without a machine to sell to other mills, but maybe I can design and sell labels. Anyway, I tested the simple method.

There are parameters, which are: Fast, Cheap, Non toxic, Non discoloring, Leaves no taste. I decided to start with cheap house brand children’s school glue. In the picture below, there is a roller with roller cover in a roller pan, my phone which served as a stopwatch, some red construction paper, which simulated the paper bag, a piece of white vinyl banner material with black lines across it, and pieces of white paper which serve as simulated labels, and the tube of glue.

I tried six labels for each timed test. I was experimenting with different methods, which slowed me down quite a bit. The most important part of this method is the white vinyl banner piece. It performed exactly as expected. The black lines are drawn with China marker, which is oil based. That way, the lines don’t wash off with the frequent washing.

The way I did it was to lay a label in each marked section of the white vinyl. then I rolled over it with the foam roller and glue. the foam roller seemed to work really well for this job. The reason for each label having its own space is to be sure no glue gets on the front of the label.  If I tried to do a second label in a space, I wouldn’t align it exactly where the first label had been, and glue would get on the front. Of course, the vinyl must be washed or wiped after each use, but that’s the price of not using a machine. The width of each space is determined by the width of the roller. In this case it was six inches long, so I made each space 7.5 inches wide.

What I do is to use the roller to lift the label after the glue has been applied. The biggest problem is that the glue makes the label curl really badly. Solvent based glue probably wouldn’t do that. Also, if there was a way to pre moisten the label, then it wouldn’t curl so bad, so long as it didn’t distort the artwork. That will need to wait for another test. The first six labels took 3 minutes, 46 seconds, which is not good. As I said, I was experimenting with methods, and in a hurry because I thought the glue was drying. The second set of six took me 3 minutes, 2 seconds, I think I could get it down to 25 seconds each pretty easily. In the picture below, you can see a line across two of the labels, about 4/5ths the way up. that’s from too much glue on the roller, the line is where I picked it up and held it while aligning it.

Speaking of alignment, I didn’t use any guideline, I just visually made it parallel with the edge of the red paper. I think that would work fastest in the end, but maybe not. The last picture is of the second set.

Update 1-16-2019 is here: I took a large aluminum cake pan, which was very flat on the bottom, and turned it over, so that I had a flat surface to work on, without being hindered by the sides. Then I spread a layer of Elmer’s glue evenly on part of it. The key is not to have it too thick. Then I took a paper label and pulled 1/2 of it through the glue. I lifted it and repeated this on the other half; then applied it to the paper envelope. This worked quite well. I can pretty much feel if there’s glue on the tips of my fingers that will get on the label. Even if it did, it will dry solid, unlike spray adhesive. I tried using spray adhesive, but there were a few problems. First, the overspray affects evrything it lands on, so I did it outdoors. If there’s a slight breeze, that’s a problem. Another problem is that any glue that gets outside the label stays tacky for a long time. This catches dust and dirt, and looks bad. The reason I was using solvent based spray adhesive was that my product wasn’t food, and wouldn’t be affected by chemicals. It doesn’t matter, the Elmers glue works great.

_Typed too soon: after the glued labels sat for awhile, the color of the yellow envelope bled through in a few places. It’s apparent that it happened where the glue was too thick, so be careful with that. The Elmers was the new clear kind, maybe I should stick with the cheap off brand school glue.

Update 1-20-2020 I went back to using the cheap school glue shown in the pictures above. I also used a credit card to spread the glue thinly and evenly on the back of the cake pan. It’s been a half hour since I applied the paper labels to the yellow envelopes, and no yellow color has bled through. this setup looks like it works well.