Hot glue coming out burnt - Page 1
Forum section: electronics / projects

author: iXod
author_rank: Frequent Contributor
timestamp: July 10, 2017, 05:50:51 am
content: Using several different glue guns. All of them are laying down glue with a brown tint.The main glue guns I use are brand names (Arrowhead), a regular size one and a "mini", using the same manufacturer's glue sticks.In USA, these are 120v units. My line voltage isn't high.Why is all the glue coming out burnt?iX

author: colinza
author_rank: Contributor
timestamp: July 10, 2017, 07:59:13 am
content: Maybe the glue just has a tint to it?

author: kalel
author_rank: Frequent Contributor
timestamp: July 10, 2017, 08:01:51 am
content: It's probably not the case for you, but the last time I had discolored glue from a glue gun, I later discovered it was the glue gun that was melting (part of the plastic). It was a cheap $1 unit however.

author: Zero999
author_rank: Super Contributor
timestamp: July 10, 2017, 08:04:52 am
content: Perhaps you have the wrong type of glue? Does the glue gun specify its maximum operating temperature? Have you checked it isn't too hot for the glue?

author: KL27x
author_rank: Super Contributor
timestamp: July 11, 2017, 12:06:02 pm
content: Glue guns are primitive things. You can spend $200.00 on a glue gun, and it will still be a fixed power affair.Assuming you have the right glue..., if the glue is still burning it's cuz your duty cycle is too low. The gun probably works great for a quick spot job where you plug it in, use it, and unplug it. Or for a production job where it is putting out a lot of glue.If you want the glue gun to work better for sitting on a bench, plugged in for long periods of time but used only intermittently, you can use a light dimmer to turn down the power. Or you can buy glue guns with an adjustable power dial. Or you can even install a properly rated switch and rectifier diode right in the handle to have full and half power.

author: Fungus
author_rank: Super Contributor
timestamp: July 11, 2017, 01:15:13 pm
content: Most glue guns will overheat the glue if you leave them sitting for a long time between squeezes.If this is the case you can either throw away a bit of glue every time you pick up the gun or get a better gun with thermostat.

author: tablatronix
author_rank: Regular Contributor
timestamp: July 11, 2017, 03:51:16 pm
content: Glue sticks come in high and low temp, maybe you have a high temp iron and low temp glue ?Maybe your glue is coated or dirty?

author: KL27x
author_rank: Super Contributor
timestamp: July 12, 2017, 07:44:21 am
content: QuoteNever yet seen a gluegun with a thermostat. I've seen fancy polymer melting guns that hold a hopper of plastic bbs and squirt out plastic like a manual 3d printer. The best I've seen on a glue gun is a power dial, not a thermostat. I have spent a hundred dollars on a glue gun... and I burnt it out in about a year, and didn't want to buy new fuse. What I got for $100.00 was a really sweet feed mechanism and base/stand. But the thing was meant to squirt hi temp glue like a fire hose. I gave myself a couple nasty burns, and I couldn't leave the thing on for more than 20 minutes without burning glue.There are CHEAP glue guns with a power dial.http://www.ebay.com/itm/120W-Electric-Heating-Craft-Hot-Melt-Glue-Gun-For-Art-Graft-Repair-Tool-US-Stock/361790433331This what I been using for several years now. I have huge doubt that it is actually 120W. Maybe if you set the dial all the way up on 220V outlet you get 120W... for a few hours before the glue turns black and the gun melts. But on 110V and set to about half power, I leave it on all day. Even when I leave it on all night, the glue doesn't burn. But it does heat up faster than the 35W glue guns I have used for years, from the hardware stores. Even with the dial on halfway. (It's too much of a bugger to turn the tiny dial up and back down again to speed up the initial heat up time.) I just turn it on and leave it on. The stand is dinky, but I have a spot on my bench where I wedge it and won't tip it over.

author: Ian.M
author_rank: Super Contributor
timestamp: July 12, 2017, 09:24:44 am
content: It really isn't rocket science to design a self-regulating glue gun heater element - just use a PTC ceramic and make sure its closely thermally coupled to the barrel. However cheap crap from China with a simple resistance wire element drives the better ones out of the market.Even if the glue gun is temperature controlled, if you hold the glue at application temperature for too long its likely to degrade, and discolouration is likely.

author: et328
author_rank: Contributor
timestamp: July 12, 2017, 11:46:33 am
content: Quote from: KL27x on July 12, 2017, 07:44:21 amSteinel Gluematic 5000?

author: Zero999
author_rank: Super Contributor
timestamp: July 12, 2017, 02:53:47 pm
content: Quote from: et328 on July 12, 2017, 11:46:33 amGoing by that, it doesn't appear to have a thermostat. It uses a PTC resistor as a heater, which is a fixed temperature heating element.

author: et328
author_rank: Contributor
timestamp: July 13, 2017, 06:28:16 am
content: Quote from: Hero999 on July 12, 2017, 02:53:47 pmIt has two PTC resistors, one (low power) is always on and the other is used at startup and turned on/off to keep the temperature constant. I actually have one sold by Lidl, not sure if it's a clone or who made it, but it has a similar circuit and PTCs and it regulates temperature correctly within a certain temp range. (a range that I modified and it's now a little too hot, originally it was too cold for good glue flow for the sticks that I use)