rubber seal strip

When it comes to stripping paint, there are three primary ways to remove paint: paint strippers, scraping/sanding, and heating. Whilst all three have their merits, in this post, we are going to be focusing on chemical paint strippers – what they are, how to use them, and their benefits.

If you want to learn more about the different ways to strip paint and whether or not you should strip paint before repainting, check out our recent post.

What is chemical paint stripper?

Paint stripper, or chemical paint stripper to give it its full name, is a chemical product designed to remove paint, varnish, and other finishes whilst also cleaning the underlying surface.

There are two main types of chemical paint stripper: caustics and solvents.

Caustic paint removers, typically sodium hydroxide (also known as caustic soda), work by breaking down the chemical bonds of the paint, usually by hydrolysis of the chain bonds of the polymers forming the paint.

Solvent paint strippers penetrate the layers of paint and break the bond between the paint and the object by swelling the paint. The active ingredient in the most effective paint strippers is dichloromethane, also called methylene chloride.

How do you use chemical paint stripper?

Depending on the type of chemical paint stripper you buy, the application will vary. Many brands come in a tin and can be applied using a paint brush.

Solvent paint strippers tend to have a gel like consistency and can be used of vertical surfaces and the gel should be applied in a thick, even coat.

CRC Strip-Off Paint Stripper comes in an aerosol spray can for easy application. The spray can application cuts down on wastage due to the accurate spray and it offers easy clean up. The spray also gets into hard-to-reach areas.

Once the gel-like substance has been applied, leave on the surface for 15 minutes to allow the paint to completely blister before removing with a scraper or steel wool.

A repeat application may be required depending on the number of paint layers present. Depending on the surface, this can then be washed down with warm soapy water, or if you are working with wood, then any residue should be allowed to dry before sanding.

You will then need to allow the surface to dry thoroughly before repainting.

Benefits of CRC Strip-Off Paint Stripper

Chemical paint strippers have a number of benefits, particularly when compared to other paint stripping options. Here are just some of the benefits of paint stripper:

Ease of use saves time
No mess aerosol application for improved user safety
Saves on brushes and containers
No wastage due to accurate spray
The thickness of the gel coat can be managed easily
Doesn't drip or run
Easy cleanup
Spray gets into hard-to-reach areas

Should you wear a respirator when using paint stripper?

The chemical ingredients in paint stripper can be potentially harmful and all precautions should be taken when using a chemical paint stripper. The primary ingredient in paint stripper is methylene chloride which can be particularly harmful. The fumes given off by paint strippers can cause respiratory problems if breathed in, so we would always recommend using a respirator or P2 disposable mask if you are working outside.

If possible, a chemical paint stripper should be used outdoors, however, where this is not possible, take all measures to ensure the room is well ventilated including opening all available windows.

Other safety gear you should wear when working with a chemical paint stripper include gloves, goggles, and protective overalls.

What mask should I wear for stripping paint?

We have already touched on this, however, we often get asked which type of mask you should use when stripping paint. Whilst this will vary depending on the type of paint stripper you are using, when using CRC Strip-Off, we recommend using type AX Filter of sufficient capacity (AS/NZS 1716 & 1715, EN 143:2000 & 149:2001, ANSI Z88 or national equivalent) when working inside (or out). If you are working outside, then a P2 disposable mask should be sufficient.

How long does paint stripper take to work?

Depending on the paint or varnish you are stripping, as well as the surface it is being removed from will determine how long it takes for paint stripper to work.

CRC Strip-Off takes anywhere from 5 minutes to 30 minutes to blister the paint or varnish on the surface, ready for removal using a scraper of steel wool.

How do you know when paint stripper is ready?

Knowing when paint stripper is ready requires assessment of the surface. The paint you are attempting to remove should have blistered sufficiently that it is easy to remove using a scraper of steel wool.

Test out a small area first to see how easy the paint comes away from the surface. If the paint stripper is ready, then the paint should come away easily from the surface without much effort.

Can you leave paint stripper overnight?

Whilst paint stripper can work effectively in 5-30 minutes, the longer you leave it, the more opportunity the stripper has to work on breaking down the paint and blistering it away from the surface.

If you are removing paint indoors using a paint stripper, we wouldn’t recommend leaving it overnight, however, if you are outdoors, then it can be beneficial to leave the paint stripper overnight for maximum impact.

How do you remove the residue after paint stripping?

After you have used a paint stripper, you will be left with a residue on the surface and it is important to either remove this residue or to let it dry.

If you are stripping paint from a robust surface such as metal, then the residue can be easily washed away with warm soapy water after you have scraped away the paint. If, however, you are working with a more delicate surface like wood, it is best to let the residue dry out completely once you have used a paint stripper to allow for repainting.

Does paint stripper need heat to work?

Removing paint with paint stripper is a different technique to removing paint using heat and so they operate independently of each other. A chemical paint stripper does not require heat to work and can be applied to cold surfaces with successful outcomes.

Many people choose to take a two-pronged approach to removing paint, especially if a thick or multi-layered surface needs to be stripped. A heat stripper is great for removing paint from large areas and this can then be followed up with a chemical paint stripper than can be used to target more intricate areas and missed patches.

What temperature should it be to strip paint?

One of the challenges of using heat to strip paint is managing the temperature of your paint stripping device.

Heat guns blast hot, concentrated air through a nozzle, and onto the directed surface. This is a highly efficient tool, that requires practice and technique to use.

Specialised infrared tools heat paint and loosen it from its substrate, but at a lower temperature than the heat gun. This minimises burning/scorching and fumes. Whilst they definitely have their benefits, infrared heat tools tend to be more expensive than heat guns and are also bulkier, making them impractical for intricate areas.

Chemical paint strippers provide a great alternative, particularly if you are working with delicate surfaces where the risk of burning and scorching with a heat gun is considered risky.

Can you use paint stripper on plastic?

CRC Strip-Off Paint Stripper should not be used on fibreglass, plastics, styrene related plastics, vinyl, Laminex, or laminated surfaces. If used to remove graffiti on painted surfaces it may also strip the base colour.

Since paint strippers are formulated to remove organic coatings, they can dissolve, etch, or otherwise destroy other organic materials such as plastics and vinyl. For this reason, using paint strippers on plastic is not a good idea.

Where to buy paint stripper NZ?

CRC Strip-Off Paint stripper is available from all leading stockists throughout New Zealand including Bunnings, NZ Safety Blackwoods, Placemakers, Repco and Mitre 10.