A guide to cover caps
Cover caps, explained
Cover caps, also known as screw head covers, screw head caps, decorative bolt head caps and nut covers, have two primary purposes:
- Protect exposed bolt, nut and screw heads from damage and ingress.
- Provide a finished appearance.
In this guide, we’ll explain these indispensable caps, covering:
Cover caps vs. cap nuts
Cover caps should not be confused with cap nuts, or nut caps. Both provide protection and a decorative appearance. The difference lies in what they’re protecting. Cover caps, as already mentioned, cover exposed bolt, nut or screw heads.
A dome nut cap, for example, covers more, specifically a bolt’s external threads. Bolt caps – or bolt covers – are usually types of cap nuts and are typically hexagonal in shape. The hexagonal shape is useful for standing up to vibration. Examples are the threaded plastic hex nut caps shown here. You’ll sometimes see these referred to as plastic nut covers, but they are not the same as cover caps.
Plastic nut caps also provide other key advantages, which is why their usage is mostly industrial, ranging from automotive to pipeline construction. Cover caps, such as plastic screw caps are commonly employed for lighter duties. Threaded screw caps are available, but these are typically low profiles.
You can learn more in our Guide to cap nuts.
The different types
Cover caps usually snap or push-fit over bolt and screw heads. Below are examples of the different types available and their uses.
- Bolt and nut cover caps
- Two pieces – base fits over the fastener head and cap snaps securely into the base
- Polypropylene (PP)
- Available in different colours – can mix and match cap and base colours
Typically used: Point-of-sale products, furniture and outdoor equipment
- Designed to protect screw heads from ingress
- Durable
- Available in LDPE, brass, HDPE, nylon and PP
Typically used: Decorative screw cap
- Fits securely over socket screw heads to protect against dust and dirt ingress
- Push fit
- Silicone or LDPE
- Available in white, black or grey
- Also known as an Allen screw cap
Typically used: Isolating metal screw heads near high-voltage cables, inside UPS boxes with limited space
- Push fit
- LDPE
- Available in white, cream, brown, light brown and teak
Typically used: Protect screw heads on veneered chipboard
- Adhesive backed for quick and easy application
- Acrylonitrile butadiene styrene (ABS)
- Available in different colours: ivory, ash, mahogany, walnut, dark oak, light oak, aluminium, white, grid patterned, pine, beech, cherry, black and grey
Typically used: Furniture
- For screws with or without a countersunk head
- Neat finish
- LDPE
- Available in white, black or grey
Typically used: Protect screw heads from damage during transit
- Protect and conceal an exposed screw or bolt head
- Provides neat finish
- Two parts – washer base and cap
- Available in high and low profiles
- PP or PE
- Available in white, black, grey, brown, orange, silver, gold-plated, stone and flint
Typically used: Furniture, metal fabrication, consumer appliances
Screw cap and bolt cap sizes
One cover cap can sometimes accommodate several different screw and bolt sizes, whether standard (imperial) or metric. It depends on the type and the manufacturer, however. Determining the size that you need is simple.
Screws are either countersunk – where the head is flush with your surface – or flat bottomed, where the bottom of the screw head is flush with your surface. Example:
Some cover caps are specific to the screw style, as we just saw in Types. That makes your choice of cap easy.
For more general caps: you already know your screw or bolt size. If using a countersunk screw, match the screw head diameter to the closest cover cap size. For flat-bottomed screws, the height of the cap becomes relevant.
Let’s say you want to use Essentra Component’s Secure Cover Caps. Here again, match your bolt and nut size and head height to find the correct cap size. Our table makes it easier for you to select the size you need, whether using standard or metric.
How to install screw caps
If your cover caps consist of two parts, such as a washer and cap:
- Place the washer over the surface hole.
- Insert the screw in the surface hole and drive it in.
- Snap or push the cap over the screw hole and washer.
If your cover cap is just that – a cap – then it’s even simpler. Once your screw is driven in, push the cap over the head. Give it a tap to ensure a secure fit.
TIP: if your caps are slightly too small to fit over the screw or bolt head, place them in the freezer for an hour or two. This will expand them. Fit them over the fastener head and they will shrink for a perfect fit.
How to remove a screw cap cover
This is also straightforward. There are two ways of doing this:
Use a small, thin flat-blade screwdriver. Push the flat blade under the cap. Lever it towards the center of the screw and lift. The cap should pop off.
This can potentially damage your surface, so consider the method used by many electricians when removing caps:
How to remove screw caps on sockets
Take a small amount of adhesive or mounting putty. Place over the cap, press and lift. It’s that easy.
Download free CADs and try before you buy
Free CADs are available for most solutions, which you can download. You can also request free samples to make sure you’ve chosen exactly what you need. If you’re not quite sure which solution will work best for your application, our experts are always happy to advise you.
Whatever your requirements, you can depend on fast despatch. Request your free samples or download free CADs now.
Questions?
Email us at sales@essentracomponents.co.uk or speak to one of our experts for further information on the ideal solution for your application 0345 528 0474.