A Granthams Guide To Self-Adhesive Vinyl - Which To Use And Why
January 16, 20194 min read
Whatever technology you use to print - UV, solvent, or latex - the chances are that in your basket of products, self-adhesive vinyl will be high up on the media list.
When picking up the phone to order and asking for the ‘usual’, do you really know why you order the type of vinyl that you do?
Self-adhesive vinyl is manufactured in a number of different ways and is designed for differing purposes.
This post is to help you find out the whats and whys about the self-adhesive products available.
Monomeric grades are the economy ranges.
Good for up to 5 years, they are designed for applying to flat surfaces.
They can though be more susceptible to shrinking and can be affected by differing climate conditions.
Too cold and they can become brittle, too hot and they can shrink.
The term monomeric derives from the use of single or short-chain plasticisers within the makeup of the media.
These plasticisers are added to the PVC mix during manufacturing and create the vinyl film’s flexibility. Without them, the film would start off hard and could shatter.
The short-chain plasticisers do not bind together in long, strong chains (hence the name), and this is why monomeric vinyl is not as pliable as other vinyl grades.
It’s also why their expected lifespan is shorter and why they will shrink and become brittle over an extended length of time.
For the short-term jobs, however, where pricing needs to be competitive and application duration short, a monomeric vinyl can be the economical go-to choice.
The next grade up is the polymeric films.
These are produced in the same way as monomers but this time instead of the plasticisers being short-chain they are, you guessed it, long-chain.
Longer chain molecules bind together within the PVC mix to create a much stronger film. They help produce a more flexible and durable vinyl and one that is less likely to shrink.
The strength within the chain also enables it to be applied to slight curves and contoured external panels without any fear of it becoming brittle over time.
It may be a step up in price but if the end product is destined to be outside in the elements for years or to be applied over contours and curves, it’s also a step up in quality.
Both monomeric and polymeric films are produced by a process called ‘calendering’.
Without going all technical, this is where the mix of PVC and plasticisers is fed through a series of rollers to create the thickness and finish of the required product.
Cast vinyl is manufactured in a very different way.
It is produced by turning the PVC mix into a liquid and allowing the component elements to bind together whilst drying.
It’s a substantially longer manufacturing process that requires a constant high temperature to cure but once the cast vinyl is produced, it's a much more durable film.
Cast vinyl is capable of being stretched using heat (vehicle wraps) and will never lose its flexibility or become brittle or crack due to the sun or the cold.
Regardless of whether the film is a monomeric, polymeric or cast, each manufacturer then applies their proprietary adhesive to the back.
This adhesive may be water-based, solvent acrylic, permanent or removable and it's as important to be aware of which adhesive is used as it is to know the actual makeup of vinyl film.
Most longer-term vinyl uses a permanent solvent adhesive for a durable grab but check when ordering to make sure that the product chosen is the right one for your intended print purpose.
It goes without saying that if you have decided to use a monomeric vinyl, use a monomeric overlaminate. The same applies for polymeric or cast vinyl.
We would also recommend the same brand or range of product for the two parts as well.
I know it’s an easy sales pitch to push the same manufacturer for both the print product and the overlaminate but in reality, if they have both been produced by the same company, you have the security that they are 100% compatible.
Mix and matching can work if the vinyl film is of the same grade but for total peace of mind, a properly matched combination will have all the guarantees for both you and your customer.
Air release vinyl
When applying self-adhesive vinyl to flat panels such as foam PVC and aluminium composite, or to vehicles and external signage, any air bubbles trapped between vinyl and substrate can be a real problem.
Some films are available with an option of an ‘air release’ adhesive to help with this issue.
The air release adhesive is made up of glue lines or dots that when smoothed out by hand, laminator or flatbed applicator (https://granthams.co.uk/blogs/news/9-reasons-why-a-flatbed-applicator-needs-to-be-on-your-print-room-shopping-list), allow the trapped air to be pushed out quickly and effectively.
For anyone that has had to use a scalpel to pop out the little bubbles across a large print, air release can be a real time saver.
Regularly create stickers that are designed to update existing signs or graphics? A grey backed vinyl can be simply stuck over the top to obscure what's underneath.
The grey back of the vinyl (it still has the same printable white face) makes for a much more opaque film that prevents any show through of the image below.
Instead of having to remove the previous work, apply the new graphics straight over the top.
Designed primarily for window graphics, these are usually polyester films (PVC does not have the optimum clarity often needed) and are reverse printed and then applied to glass.
Ensure these have a solvent adhesive as a waterbased glue will ‘cloud’ for a day or two.
We’re starting to see window materials using ‘micro suckers’ with no traditional adhesive at all which makes the removal and re-application super simple.
I’ll write a later post looking at these new innovative products.
It’s important that not only do you have the most effective and efficient print machines but that you’re also are using the most productive products through it.
This is why we’re creating these posts to help cut through the jargon when it comes to media options.
If there is anything you think we’ve missed in this post or anything you’d like to know more about in future posts, let us know on our Facebook page or email us at email@example.com