Important information about glue and magnets
Magnets, metal and glue
If you want to glue magnet or metal discs on to a surface to make your non-magnetic item magnetic, there are some things you need to know about both the gluing process and especially about cleaning the surface first.
Here is our best advice - remember to read the intire post to make sure that you will succeed (so you do not have to deal with magnets falling down):
Cleaning the surface
In order to glue a magnet or metal disc onto any kind of surface, you will first need to make sure that both areas are clean and dry, and that the surface of the magnet (or metal) is scratched with fine-grained sandpaper to give it a better grip for the glue. The best way to make sure that your surface is clean is by using Isopropyl Alcohol. It will leave your surface clean without any membrane. Never use just water and soap or rubbing alcohol from the household as it will not be effective enough and might leave a membrane.
If you have a smooth surface (eg. glass, metal or acrylic), you will also need to scratch this first with fine-grained sandpaper to give a better grip for the glue. And remember to clean the surface with Isopropyl Alcohol as the last step.
All products Important information about glue and magnets
Application pressure of 1-2 kg.
The magnets (or metal plates) must be mounted with an evenly application pressure of 1-2 kg per cm2. In other words: you have to put strength into making an "evenly distributed" pressure over the entire surface that needs to be glued. If it is a square magnet or metal plate, you can use several fingers to press it firmly in place.
It is important that the magnet is pressed all the way down from the start, so that no oxygen gets to "the core" of the glue: Oxygen will interrupt the curing process with the risk of having to start all over again from step 1 with cleaning the surface.
If you need to glue a big magnet or metal disc, you can use a heavy object such as a bottle, a cake roll, a book or a toolbox to make the pressure firm and evenly.
Drying time for the glue
3 days of rest (72 hours) is the most optimal drying time for the glue. In that period of time, the glue will be able to harden completely.
It depends a lot on the glue type, how long you will have to keep the pressure before it grips both the surface and the item being glued (magnet or metal disc). If you use the UHU Max Repair Superglue, which is suitable for magnets, it takes approx. 5 minutes for the glue to get a full grip, which gives you time to move the item around a bit. Self-adhesive gets a full grip in less than a minute. But remember to make sure that no oxygen is added so that the hardening process stops.
The strength of the glue builds up during the first 24 hours. And over the next few days, it sticks so well that it is almost impossible to get off again (see point below if you need to remove any glue).
Protective foil on the surface?
Materials such as acrylic, polycarbonate etc. often come with a protective foil on top to protect the surface from bumps and scratches. This foil must be removed before gluing and the surface must degass completely. Gases on the surface destroy the chemical hardening process of the glue, and it will be close to impossible to glue e.g. an acrylic sheet up right after you have lifted the protective foil off. Leave the plate without foil for at least 24 hours before gluing (applies to all types of glue and self-adhesive tape).
And always remember to clean with Isopropyl Alcohol before gluing. You can not use regular rubbing alcohol (see the section about cleaning surfaces at the top of this post).
Wood surfaces must be primed first
Untreated wood surfaces need be primed before they can be mounted with 3M self-adhesive or with glue. If you have a ready primed or painted wooden surface, you will need to scratch lightly on the surface for the glue to grip. And always remember to clean with Isopropyl Alcohol before gluing.
Optimal gluing temperature
The perfect drying temperature is 15-20°C for both 3M self-adhesive and UHU superglue. The hardening process of the glue will stop if the temperature drops below 13°C. Whether it is a magnet, metal or something completely different, a normal room temperature is an optimal temperature when you need to use glue and self-adhesive.
How to remove glue
If you use a strong glue and want to remove it again, fortunately you have a few options to succeed with this. However, we only write about the types used for magnets and metal in this post.
When you have mounted something with UHU Max Repair Superglue and want it down again - e.g. if you have glued metal or a magnet to the wall - please do not remove it with a screwdriver: the glue just needs to be heated up to above 50°C, and this can easily be done with a hair dryer.
The exact temperature for being able to remove the glue depends on the room in which you glued the magnet or metal, as well as the surface on which you glued: if it is a very cold room or a very hot room, the glue has "adapted" to the temperature over time. But in approx. 8 out of 10 cases, you can just use a hair dryer. And besides being an easy and accessible thing to grab and avoiding a ripped surface, you also do not ruin the magnetism in your magnet with a hair dryer as magnets can withstand up to 80°C.
In relation to the surface you have glued on, there is of course a big difference between glass, wood and metal. Rough surfaces give the glue incredibly good conditions for getting stuck. In this case, you may need a bit of help from a screwdriver also to help loosen the magnet or metal disc a bit. But still: let the hair dryer do most of the work.
Removing self-adhesive / double-sided adhesive tape
The hair dryer is also your friend in terms of removing 3M self-adhesive: gently heat with the hair dryer around the item and after a few minutes, you are ready to wiggle your items apart.
However, you must be aware that with double-sided 3M adhesive, there may be some residue left on the wall. But in most cases, this can easily be "rolled off" with one finger and some patience. If it is very stuck, we can recommend a scraper (the one you know from setting up foil, but a solid dough scraper or a credid card can also be used to push the remains of the 3M adhesive off with).
Does the glue still give you challenges?
Glue has become a big part of our customer service knowledge base as we advise in many projects where non-magnetic things have to be made magnetic. And this often requires either screws or glue. We are therefore a part of an ERFA group where we can get help when we ourselves fall short of knowledge in a situation. Also, we are in close dialogue with our suppliers of self-adhesive regarding our own products. So we would very much like to hear from you if you are struggling to get a glued item down again with the methods we have described above. Then we will do our best to advise you, as long as it has to do with your order from us and you provide us with a thorough description of your challenges.
If you are in doubt about the use of glue and 3M self-adhesive for your magnetic project, please do not hessitate to contact us. Our customer service has opening hours every weekday and would very much like to guide you.