Keeping the Glue Pot Clean

This thread starts with a question about glue brands, but evolves into a discussion about how to operate the glue-pot edgebander to avoid charring of glue and reduce the need for cleaning the equipment. November 2, 2010

I'm thinking about switching over to Helmitin #498 "Seamless" hot melt pellets. They are supposed to be unfilled, but opaque, to work better with light colored materials than clear hot melt, provide a nearly-invisible glue line, and not require changing glue colors when switching between panel materials. Has anyone out there had experience with this or similar adhesives? I'm running mostly white melamine, with the occasional prefinished maple ply job, and a rare dark material project from time to time.

Forum Responses
(Cabinetmaking Forum)
From contributor C:
I run strictly Jowat clear on everything. It was what the manufacturer spec'd when I bought the machine. Every time I buy a Helmitin product, my guys always remind me of the last time we bought it and make me ship it back.

From the original questioner:
What does your glue line look like in a white-on-white situation? The clear adhesive I've seen shows a darkish line with light colors. What particularly was wrong with the Helmetin products? I've only used their PVA glue, which was fine.

From contributor C:
I can barely see it and I'm serious. We run so much product at such a fast pace I really don't pay attention to it. Contact cement - comparable to Conbond- my guys just hate it. So if I even bring in something with their label on it they scream bloody murder about we know what works.

From contributor Z:
I use the Jowat clear as well on all colors. I cannot see any glue line. Maybe you are running it too thick or pressure roller needs adjusting. If you are using a lot of glue in any color, it will darken in the pot and give a more visible line. I keep a very low amount of glue in the pot at all times and add frequently. No charade glue on the side of the pot and the color stays clear. Less warm up time as well and I only clean the pot every second year.

From contributor X:
You only clean your glue pot once every two years! Please, let us know the part # your using. I use #288.60 which is a filled EVA and clean my pot 3-4 times per year.

From contributor M:
We use the same clear glue (Dorus KS208) on everything from white to black, and I have not noticed any glue lines. We have only cleaned the pot on our Brandt two times in ten years and one of the two, (last time) was because of a bad glue batch, about three years ago. I absolutely insist that the glue pot gets turned off if not being used for a few minutes, 3-5 or so and the glue gets replenished frequently. Also, two people normally operate the edgebander, one feeds material and one catches it - in the interest of keeping the edgebander operating at a minimum. The time we got the bad glue, Edgebanding Services sent us a product that looked like the glue pellets which were placed in the glue pot, heated and it melted the old glue.

From contributor Z:
As you can see from Contributor M's posting, it is possible to keep a pot clean for a long time. It does not matter which glue you use. Assuming you are starting with a clean pot just follow these guidelines; keep in mind i have only one employee part time and am not a big shop.

1. Keep as little glue in the pot as you need to do the job and add small amounts often.

2. Turn off heater as soon as you are finished using the machine.

3. Keep parts that are external like glue roller area spotless with thinner. Clean area daily.

4. Always use dust collection.

5. I keep my temp at 200 Degrees max.

Not all machines are the same, but in my EP-9 there is a rectangular opening at the back of the pot when you look inside. This is where the glue flows to the roller area. 75% of this rectangular slot should be visible at all times. This way the flow of glue is added by the air around the flow and the smoother the flow the less chance for glue buildup and charring in the pot. Keep PVC dust and particles out of the pot by making sure the heat cover is always on and that the glue storage bag or bucket stays sealed.

From contributor C:
We donít clean our pot except to change the bearing, heating elements and clean the auger every four years. We turn the bander off when not in use. We make sure everyone is trained to run the glue down and to check it regularly and add small amounts. This keeps it from becoming vulcanized goo.

From the original questioner:
I keep my gluepot as full as possible, which eliminates charring on the gluepot sides-glue roller seems to apply more evenly and consistently as well. I've been running Dorus 205 at about 210c; Helmitin recommends about 180 for their seamless which I think would be advantageous for glue life and maintenance.

From contributor F:
I havenít had my bander for too long and have yet to clean the pot. I was told to stick a broom handle in a let it cool the pull the glue out as its warming up using the broom handle. I like the idea of those additives instead. Just need to look in to where I can buy them locally.

From the original questioner:
How do you guys who use the cleaning pellets flush the stuff out of the system once you've used it? It sounds like a great idea, but I'd be concerned about contaminating the new glue with whatever residue is left after cleaning.

I've heard both sides of the full-as-possible/low-as-possible glue pot level debate, and my logic is that a filled pot has the smallest surface area exposed to oxygen, so should burn less. I tend to run 300-400 feet of banding at a time, usually once a week (not counting the inevitable short-run after a screw-up), so the glue probably runs through the machine without a large number of repeated heatings.

For what itís worth, the Helmitin tech recommends keeping the pot full. Those of you who are anti-Helmitin might want to do the opposite. Keeping the machine off when not in use and turning the heaters off when idling helps with glue pot cleanliness. I clean mine out every six months or so which probably translates to 6000-8000 feet of banding.

From Jeff Pitcher, forum technical advisor:
I'd suggest keeping the glue pots relatively full. The real key to avoiding charring is not "cooking" the glue in the pot. All hot melts degrade with long term exposure to heat. If you're not using the machine turn the temperature way down or off. This is part of the reason Holz-Her has been successful with their machines because they basically melt the glue on demand. I've seen some retro-fit kits that will allow you to do this. Also, I believe Jowat sells some cleaning agents that work well for cleaning out charred pots.

From contributor L:
A lot seems to depend on what machine you've got and how much you run it. We have a bigger machine and never clean the pot. The glue level is automatically maintained in the pot and the pot is relatively small. Add to the fact that the machine automatically lowers the temperature if the machine is idle for a few minutes and you get very little charring. The tower portion of the glue pot is cleaned every three months. We run about 1000' a day so glue doesn't stay in the pot long. There is a hopper that holds enough pellets for constant run all day. The machine senses the level and preheats the required amount as the level goes down. This would be similar to the guys that add small amounts to keep their pots at a constant level.

From contributor E:
I have run, and maintained our banders for 25 years or more. We used to have a Stefani and now we have an Adwood EP-8. What I have found, is whether one keeps the pot full or half full is not as much the issue to prevent charring. The real issue is religiously maintaining whatever level you choose. You will note that the charring that occurs on the glue pot itself.

It happens wherever there is not a "heat sink" of glue. Accordingly if one normally keeps the pot 3/4 full and then lets it drop to 1/2 full, and fails to replenish the glue you will see that the exposed glue on the side of the pot rapidly vulcanizes and burns. Maintaining the same level at all times, coupled with conscientious reduction of heat will give the longest times between cleanings.

We have used the adwood cleaners with good success. They look like bars of soap, when they are heated and pumped through the pot they turn clear and have thin viscosity. After using the cleaner, we used paper towels to sop the final bit in the bottom of the pot.

One more thing that is tough on glue pots is if the pencil heaters in the glue head are left on too long without glue being pumped through the head. The head will char inside and burnt particles will begin dislodging and plugging the glue spreader. Generally the only solution is a complete disassembly and cleaning (we soak the head in xylene, overnight in a covered container). The old glue and char swells and sloughs off. It might not be the gospel, but I hope this information is helpful to someone out there.