10 tips for storing paints, varnishes and glues
After a project has been completed, there are often leftover stains, paints or glue mixtures that are to be used later. And just as often, these paints or adhesives are unusable when they are to be used again. To prevent this from happening to you in future, we have put together the following 10 tips for the correct storage of paints, varnishes and glues:
1. buy appropriately
As early as the project planning stage, you can ensure that only a small amount of paint or varnish is left over. Calculate the surface to be treated and only buy the right amount. The consumption per square metre is precisely indicated on the packaging of most surface products
2 Mix the colours yourself
Pre-mixed colours generally last significantly less than the pure individual elements. Many waxes, oils and pigments last for several years when unmixed. This is particularly true of paints and adhesives that are offered as two-component systems (resin and hardener). Always mix only as much as you actually need. At DICTUM, for example, you can obtain all components for mixing Linseed oil paints and Milk paints as well as Oils and Waxes in different container sizes. You can find recipes for mixing colours and surface agents in our free Surface primer.
3. cleanliness right from the start
Ensure cleanliness right from the start. No preservatives are added to most emulsion paints or water-soluble paints and glues, so their shelf life decreases continuously once the container has been opened.
Unclean brushes or paint rollers introduce bacteria and germs into the dispersion and these gradually decompose the ingredients. The binders are decomposed first and then the pigments. As a result, paints first lose their processing properties such as spreadability and adhesion and then the colour tone changes. With self-mixed glutin glues, i.e. bone and hide glues, germs or spores ensure that glue residues quickly start to mould.
Tip: Clean a new paintbrush or paint roller before use. A freshly cleaned, slightly damp brush absorbs less paint or glue and is easier to clean afterwards!
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4 Store in a cool and dry place
It is almost always written on the packaging: Store in a cool, dry place. But what exactly does this mean? Most paints, varnishes and glues can be stored well at a constant room temperature of 15 to 20 °C. Cellars are ideal for this as they usually remain cool even in summer. Cellars are ideal for this, as they usually remain cool even in summer. If you don't have a cool room, you can store paints and glues in a refrigerator. This does not have to be locked. The main thing is that the temperature remains constantly below 20 °C due to the insulation of the cupboard.
Superglues in particular (cyanoacrylate adhesives) last much longer at low temperatures. However, ready-mixed two-component glues can also be stored for longer in the refrigerator at temperatures around 7 °C, as the low temperatures reduce their reactivity.
Leftover homemade bone and hide glues can be stored in the refrigerator for a few days. These glutin glues should be treated like food, they are basically gelatine. After a few days, however, bone glue starts to mould, even in the refrigerator. The shelf life of glutin glues can be extended by adding a little citric acid.
Be careful with normal wood glue or white glue! These are dispersions that do not tolerate cold well. Depending on the brand and manufacturer, they lose their adhesive strength at temperatures below 5 to 10 °C. We have already written a blog post on this topic: Please heat the cold workshop!
5. switch off the lights, let the air out
Many paints, varnishes, oils and glues need air and/or light to set or harden. In the case of dispersions, the water evaporates into the air or is absorbed by the wood. Superglues and PU glues react with moisture in the air or in the wood. Linseed oil paints only harden or polymerise completely with sufficient UV light and air supply. When storing, it is therefore advantageous to transfer leftovers into a lightproof and airtight container. For example, patented lidded tins are ideal. These are easy to fill, seal airtight and lightproof and are available in different sizes.
Caution: The tip is often given to turn the cans upside down so that no air gets into the container. However, it can happen that the can is not really airtight or that some paint sticks to the edge of the lid. When the paint dries, the lid sticks to the shelf. When you take it out, the contents spill over the shelf onto the floor... If you follow this tip, always place a cardboard box or, better still, a small bowl under the tin (newspaper is too thin). If some of the paint leaks out, you can turn everything over together with the cardboard or tray and then open the tin safely.
It is easier to cover the paint with water or thinner. The layer of water or solvent prevents a skin from forming and is simply tipped off or stirred in before the next use.
If a skin has formed, check how thick the skin is. You can carefully remove a thin skin with a stick and then pour the paint through a disposable sieve or a thin nylon stocking into another container.
Oils and colours can be stored in so-called StopLossBags with virtually no trapped air. No skin can form in them as the air is simply pressed out of the bag after filling. The StopLossBags are filled using a suitable funnel, on which many cans fit perfectly so that nothing spills out.
There are practical glue dispensers for wood glues. Classic white glues are dispersion glues that harden by evaporation. Many glue dispensers therefore have a larger storage container and only a relatively small opening for processing, through which little can evaporate. With the glue dispenser GluBot, for example , the glue is in a thin riser tube and can be conveyed out by pressing on the storage container.
The classicglue boy also works according to this principle. It also has an airtight glue container. In front of it is a small glue basin for the brush. A cover can be used to close the basin, including the glue brush, and protect the glue and the water it contains from evaporating.
Superglue and PU glue or all adhesives that react with moisture in the air cannot simply be decanted. When decanting, they would come into contact with a lot of humidity and become unusable. After use, it is best to squeeze as much air out of the bottle as possible and close everything tightly.
6. choose the right container and cap
In addition to the size of the container, the material it is made of also plays an important role. Some paints and glues react to metal, others attack plastic. For example, when gluing wood containing tannins, dark stains can occur if the glue comes into contact with metal. We therefore recommend using a cord composite instead of a metal clamp forglue brushes. Shellac also reacts to metals and should therefore be stored inplastic containers or apothecary bottles with glass caps.
7 Pay attention to safety
Although the regulations of the employers' liability insurance association only apply to professionals, according to the BG, only unbreakable and sealed containers may be used to store coating materials - i.e. not jam jars. In the hobby workshop, you do not have to comply with the BG, but even here a jar can break if it falls. The containers, cans and bags mentioned above are ideal.
Never decant coating materials, solvents or adhesives into food containers and store them there. This can be fatal! Adhesives, paints and varnishes must always be kept out of the reach of children!
In this context, also observe the hazardous substance labelling on the packaging. Empty and partially empty containers of flammable paints or solvents almost always contain explosive gas mixtures. Therefore, do not smoke or handle with fire when filling and working and always ensure adequate ventilation.
8 Labelling the contents
Always note on the container which substance it is (emulsion paint, stain, glue, etc.), the colour, the intended use and the date if applicable. This makes it easy to find the right colour/adhesive for repairs or other projects. Without sufficient labelling, it is often no longer possible to identify the right product after a few months, especially if you have kept several leftovers.
9. note the expiry date
In general, water-soluble paints and varnishes have a longer shelf life than paints containing solvents. Ready-to-use paints, varnishes and glues are usually labelled by the manufacturer with an expiry date or period. At DICTUM, for example, we state that glues can be used for at least 6 or 12 months after purchase, depending on the type and manufacturer. Similar to the best-before date for food, which is often still edible for a certain time after the best-before date has expired, the properties of glues and varnishes also gradually change after expiry. Adhesion is usually the first to suffer. Although the paint or glue still looks normal, it no longer adheres properly to the surface or no longer hardens completely. Spoilt paints and glues can be quickly recognised by their smell. If a paint or glue smells funny, sour or foul, it must be disposed of. Even adding a new solvent or binding agent will not make the spoilt ingredients usable again.
10. dispose of properly
Dried paints, varnishes and glues can generally be disposed of with household waste. The situation is different for liquid residues. These must be taken to a recycling centre for the collection of hazardous substances. Even small residual quantities must not simply be disposed of down the drain. Paints, varnishes and glues can stick together in pipes or siphons and cause blockages. In addition, sewage treatment plants can have real problems with some paints and solvents. It is therefore best to spread small amounts of paint and varnish residue on a scrap piece of wood or cardboard and leave to dry. You can then dispose of the dried residues with household waste. However, always follow the manufacturer's disposal instructions!
For more information about glues and materials, we offer an online course on this topic: Glues and adhesives in the wood workshop.
