Three truths I’ve never told my customers about selling hot melt adhesives for 13 years! The secret to the non-delamination of book and periodical binding!

Let me start with a true story that I’ve been remembering for eight years.

In the winter of 2016, a printing factory owner called me at 11 a.m. and started off by saying, “Brother Shu, something big has happened. The 50,000 textbooks I just bound have their adhesive ridges broken on the first page. The Education Commission is coming to inspect them tomorrow!”

I asked, “Did you use the same pot of old glue before turning it on this time and reheat it repeatedly for at least three or four days?”

There was a silence of five seconds on the other side. “… How do you know?”

How do I know? Because this pot of glue has turned into “glue residue mixed with rice” – it still looks like it can be stretched on the outside, but the inside has long carbonized and denatured. What’s the difference between using this kind of thing to stick books and using expired 502 glue to stick leather shoes?

That night, I put on my clothes and rushed to his factory. In the end, I managed to rescue 30,000 copies with an emergency plan. But I’m not here today to brag about how great I am. I’m here to tell you the truth.

Three truths that I have been hiding in the industry for 13 years are all revealed today.

Truth One: What you bought was not glue at all, but “stone powder with a more pleasant name”.

Saying this might ruin the jobs of my colleagues, but I don’t care about that much anymore.

If you ask ten salespeople selling hot melt adhesive, “Why is your adhesive three yuan cheaper than others’?” Nine out of ten will tell you, “Our formula is good and the cost control is good.”

“Damn it!”

Take the cheap glue for testing to see what the proportion of calcium carbonate and talcum powder is inside. The most outrageous thing I’ve ever seen is that when the filler is added to over 40%, the glue stick breaks into two pieces when dropped on the ground, and it’s as crispy as a biscuit.

These people are not selling glue; they are selling stone powder.   It’s just that the stone powder has been dressed up in a “hot melt adhesive” disguise.

When you first use this glue, you won’t notice it. Its fluidity is even smoother than that of good glue. But three months later, when you look at it again, the spine of the book is as hard as old cured meat. When you turn it over in winter, with a “click”, the adhesive layer is completely torn apart.

I’ll tell you a folk remedy that works better than any test report:

Melt the glue and pour it onto a piece of white paper. Wait for it to cool and solidify, then throw it into the freezer of your refrigerator and let it freeze for half an hour. Take it out and fold it in half.

Good glue: Like a rubber band, it doesn’t crack when folded 180 degrees. Even if you tear the paper, the glue remains attached. Poor-quality glue: It either freezes so hard that it breaks easily when folded, or it can’t be pulled into threads at all, falling off in pieces like wall plaster.

Those suppliers of cheap glue never dare to let you do this test. Why? Because they themselves are well aware that a refrigerator at minus 18 degrees Celsius is the “magic mirror” that reveals their products.

When you bought the glue, you were shrewd in your calculations and it was several hundred yuan cheaper per ton. But have you ever thought that a single return or a quality accident would cost you a year’s worth of profits?

Truth Two: Don’t be fooled by “high viscosity”. The soul of book and periodical glue is “flexibility”

This one is the cancer recognized by the industry. I’m going to operate on it today.

Most printing factory owners, when buying glue, immediately ask, “What’s the viscosity of your glue?” Is the wire drawing long?”

Brother, you’re sticking books, not tiles. Have you ever seen a book whose pages fell off because of insufficient glue? Hardly any.

The number one culprit for page loss in books and periodicals is always insufficient flexibility.

Let me give you an analogy and you’ll understand.

A textbook is transported from a warehouse in Harbin at minus thirty degrees Celsius in winter to a classroom in Hainan at thirty degrees Celsius, with a temperature difference of 60 degrees. If your glue becomes brittle at low temperatures and soft at high temperatures, the stress and pulling force generated inside the glue layer during this round of logistics will be greater than the force your wife pulls your ear. It would be a ghost if the book didn’t drop pages.

But if you look through the test reports of those adhesives, how many of them will honestly tell you what the low-temperature brittleness temperature is? How many companies dare to promise you that the temperature tolerance range is from negative to positive degrees?

Most salespeople will only show you a rubber stick and stretch it to one meter long, saying, “Look at how good the viscosity is.”

Let me tell you, the filament drawing only indicates the melt index and has nothing to do with whether the book is good or not. The truly good glue is the kind that when you open a book 180 degrees and press the middle of the spine with your thumb, the glue layer does not delaminate, break or spring apart.

So next time you buy glue, don’t ask about its viscosity. Just ask three sentences:

What is the softening point of your glue? It tends to become sticky in summer when the temperature is below 75 degrees, and machines age faster when the temperature is above 110 degrees.



At what low temperature can the pages remain soft and not fall off? (-10 degrees, this is a hard indicator)


How many years has the aging test been conducted? (Three years without delamination is considered passing the passing line.

If the other party stammers and can’t answer, just turn around and leave. Don’t waste your time.

Truth Three: At least Half of the delaminated pot is cooked by yourself

This sentence is the most offensive, but I must say it.

I’ve seen too many bosses call the glue manufacturer immediately when there’s a problem: “Your glue is not good!” ”

When I went to the scene to take a look, all the problems lay in my own operation. The three most typical suicidal operations:

First, the temperature got out of control. You set the temperature of your glue tank to 180 degrees or even 190 degrees, yet still think that “the higher the temperature, the smoother the glue.” Big brother, that’s not about boiling rubber; that’s about boiling asphalt. Hot melt adhesive is most afraid of prolonged heating at high temperatures. For every additional hour of boiling above 160 degrees, the polymer chains start to break, the color of the adhesive changes from light yellow to dark brown, and the bonding strength drops by more than 20%. If you smell that pungent odor, it means the glue is “burned to death”.

Second, repeatedly reheat. I didn’t clean the glue tank when I got off work today. I’ll continue to add new glue when I turn it on tomorrow. Do you think you’re stewing old brine? The old glue at the bottom of that pot has been heated repeatedly for dozens of hours. The carbonized particles are mixed in the new glue, which is equivalent to adding sand to the glue. The books glued with this kind of glue have a smooth spine surface, but inside they are full of stress concentration points and will crack as soon as they are turned over.

Third, cleaning depends entirely on one’s mood. I once saw a rubber tank in a factory. The residue scraped off was as hard as asphalt blocks. The master told me, “It hasn’t been cleaned for half a year. Anyway, it can still be used.” I’d like to ask this master, if your wok hasn’t been cleaned for half a year, would you still dare to pour new oil into it for stir-frying?

Here’s a foolproof operation standard for you. Stick it beside the machine:

Glue temperature: 150-160 degrees in summer and 160-170 degrees in winter, not exceeding 170 degrees.
• Tank cleaning: If the machine has been shut down for more than 4 hours, the rubber tank must be emptied.
• Refilling the glue: Refilling can only be done when the new glue in each pot has been consumed by more than 70%. It is not allowed to only refill the bottom layer of the pot.
• Thorough cleaning: At least once a month, scrape off all carbides on the glue tank and rollers.

If you can achieve these four points, the degumming rate can be directly reduced by half. If you can’t do it, no matter how good the glue is, it’s all in vain.

Finally, let me say something from the bottom of my heart.

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I have been selling hot melt adhesives for 13 years and I understand one truth best:

Customers don’t come back because the glue is cheap, but because the pages of the book don’t fall off.

Those colleagues who teach you to add more fillers to the glue to reduce costs, the glue they use in their own factories is not from the same batch as what you buy. The water in this field is just this deep.

I’m leaving all three truths here today. It’s sure to offend people. But I think it’s worth it – because this industry is not short of glue sellers, but what it lacks are those who dare to speak the truth.

You may not believe me, but you must do the refrigerator test once. Once it’s done, you’ll know who’s selling glue and who’s selling stone powder.