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The Importance of Primers

by Jack Carr


Prime, prime, prime and prime.

That one single word is something our Training & Applications Manager Gill Harrison drills into delegates on our training courses. For good reason! But its also one of the most frequently asked questions too, so there is still a lot of confusion over what to prime, when to prime and how to prime. So we are going to look at explaining the process to guide you through the minefield.

The importance of priming cannot be underestimated. It can be the difference between the success and failure of a project. In this blog we will take you through;

  • Why primers are so important
  • Where to use primers
  • Top tips to remember when using primers

Why primers are so important

So. Why are primers important?

It’s quite simple really. Ask yourself this. You have a big bar refit coming up using architectural finishes, what is the last thing you want to happen? Its failure isn’t it? Any material failure is costly for you and your business, in terms of time and replacement costs which we all want to avoid. Well. As the old saying goes, ‘Fail to prepare, prepare to fail’. And that’s no different in this case.

Using the correct primer in the correct areas (which we’ll get onto) will help minimize the dreaded shrinkage and promote increased adhesion.  A primer applied to a substrate before applying film helps achieve a good bond between the substrate itself and the film.

And that’s about it. Knowing why primers are important is easy. Knowing where to use them. Not so much.

Where to use primers

If in doubt, prime. Is a good rule of thumb to have. But let’s investigate some areas where priming is an absolute must.

Think about the shape you are wrapping. If you are stretching the material, you need to prime! Joining materials? You need to prime! For overlaps the very bottom layer against the substrate and in between both layers of vinyl must be primed. Beware when using splice joints, the substrate must also be primed too.

Use your own initiative. Don’t get lazy. For example, you are wrapping a door, you need to prime any areas where moving parts will be refit after the install, e.g. handles and coat hooks. The movement within these areas may cause the vinyl to lift over time.

And don’t forget about ends, corners or edges! Prime them all. Think about any high risk areas where you think traffic and usage may be higher, get it primed! It’s all about risk avoidance.

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Top Tips

You now know why priming is so crucial for a successful install. Here’s some top tips to ensure you’re priming right…..

Choosing the right primer

So how do you know which primer to use for which surface? I hear you ask.

Well. There are different primers available for use on hard or porous surfaces, as well as for both brands of architectural finishes, meaning you need to select the appropriate primer for each install. There isn’t just one for all application. William Smith stock 5 different primers including; Cover Styl’ Primer, Cover Styl’ Primer Plus3M Primer 94, 3M WP 2000 and 3M WP 3000.

These various primers have different characteristics meaning some are more suitable for use on certain substrates than others.  The table below provides a good overview of an example of primers we have and their suitability to certain substrates, as well as the dilution factor required!




Dilution Factor

3M Primer 94


  • Gypsum board
  • Calcium Silicate (with sealer
  • coating)
  • Plywood
  • MDF board
  • Aluminium
  • Stainless steel
  • Painted or coated metals
  • Films (including DI-NOC films)
  • PVC laminated steel
  • Mortar (with sealer coating)
  • Painted or coated metals

Do not dilute



  • Gypsum board
  • Calcium Silicate (with sealer coating)
  • Plywood

Maximum 3 parts water to 1 part primer



  • Plywood
  • MDF board
  • Painted or coated metals etc.
  • Ideal for small areas – higher bond than WP-2000

Do not dilute if applied onto metal

For MDF or wood, dilute 1 part water to 1 part primer


Cover Styl’

  • Any absorbent surface
  • MDF
  • Plasterboard

Do not dilute

Primer Plus

Cover Styl’

  • Any hard surface
  • Worktops
  • Laminated doors etc

Do not dilute

Another great way to remember which primer will be suitable, is to think about what it comes in. Primers in a hard tin are solvent based and designed for use on hard surfaces, whereas primers in a soft plastic bottle are water based for porous surfaces. Simple.

When can you apply film after priming?

This is key. Don’t forget ventilation after using primers! Allow the primers to dry first. You can use a heat gun to help speed up drying times too.

But. To answer the question; when can you apply film after priming? Generally speaking, you are looking at around 15-30 minutes to allow the primer to fully dry. Factor this into your installation time.

There is an exception to this rule though. If the temperature is below 10 degrees in the installation environment, you need to leave 2-3 hours after applying primer before you apply architectural film. This is to fully allow the primer to dry in colder temperatures.

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Does primer affect application?

It’s a good question. And the answer is a bit vague. It can sometimes affect application of film afterwards (depending on the substrate), so you must be careful.

By its very nature, the use of primer causes a significant increase in adhesion force. Repositioning of the film during application will be difficult on primed areas and can even cause damage to the substrate below the primer. You may not get a second chance, especially on emulsion walls!

Therefore, we recommend you take a pre-application inspection of the substrate, looking for any risk factors first. If you take all things into consideration you can take the right precautions and avoid any dramas further down the line. You could even do a test application? And really make sure your application is bang on!

As I’m sure you will now agree, there is a lot more than initially meets the eye with Primers. They are such an integral part of an architectural film project.

The expert team at William Smith are on hand to help with queries or questions you have about Primers. Please don’t hesitate to get in touch by calling us at 01833 690305, or by email info@williamsmith.co.uk.

From the blog

by Jack Carr
by Lindsay Appleton

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