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Why Can’t You Use Plumbers Putty on Plastics: The Primary Reasons

Plumber’s putty has been a staple in the toolkits of plumbers and professionals. This clay-like substance is always preferable for watertight sealings on any faucets, sinks, or drains. However, you can’t use this product on plastic materials like PVC or ABS.

But why can’t you use plumbers putty on plastic? Plumber’s putty is unsuitable for plastics as linseed oil can seep into it and cause it to weaken and deteriorate over time. Also, plastic can react chemically with putty, which makes plastics brittle and less effective for a long time.

That’s why it’s advised to avoid using it on plastics. Then what can you use as an alternative to plumber putty? Keep reading to learn about potential risks, reasons for avoiding it, and the best alternatives to plumber putty.

Reasons Behind Why Can’t You Use Plumbers Putty on Plastics

why can't you use plumbers putty on plastics

There are several reasons why plumbers’ putty is not suitable for use on plastics. These reasons are quite convincing and include the following:

Chemical Reactions

The oil-based composition present in both plastic and plumber is the primary cause of their incompatibility. Polyvinyl chloride (PVC), chlorinated polyvinyl chloride (CPVC), and acrylonitrile-butadiene-styrene (ABS) are some of the commonly used plastics in plumbing systems.

However, these materials are susceptible to the oils and chemicals contained in plumber’s putty, rendering them unsuitable for use as a sealant in such applications.

Incompatibility with Plastic Materials

Plumber’s putty may not adhere well to certain plastics, resulting in a poor seal and an increased risk of leaks. It’s crucial to ensure proper sealing in all plumbing systems to prevent leaks and maintain their overall integrity.

A deficient or ineffective seal may result in water damage, mold growth, and costly repairs in the future.

Therefore, it is vital to use suitable sealants and techniques to guarantee the best possible results and avoid any potential hazards.


Plumber’s putty contains high calcitic lime, oils, and other substances that have a tendency to penetrate the plastic material. This can cause unsightly stains or discoloration that are often challenging to remove.

Such an issue can be especially troublesome in visible areas, such as exposed pipes or fittings located in kitchens and bathrooms.

Therefore, it is crucial to use appropriate sealants that do not contain any substances that may discolor or damage the plastic, ensuring a long-lasting, visually appealing finish.

Alternative Sealants: Better Options for Plastic Pipes and Fittings

Instead of plumber’s putty, there are several alternatives that are more suitable for use on plastic pipes and fittings. These alternatives provide better adhesion and compatibility with plastic materials, ensuring a proper seal and minimizing the risk of leaks. Some options include.

Silicone-Based Sealants

One popular option of an alternative sealant for plumber putty is- silicone-based sealants. These are specifically formulated to create a strong and watertight seal on plastic pipes and fittings.

Not only does it create a watertight seal, but it also possesses strong adhesive properties that a plumber’s putty lacks. However, it lasts less than plumber putty and is not very flexible.

PVC primer

When it comes to joining plastic pipes, PVC primer is an ideal choice. Typically consisting of acetone and cyclohexanone, the PVC primer is capable of removing the outer sheen of the pipe, creating a roughened exterior that facilitates the adherence of PVC glue.

The acetone or tetrahydrofuran in the PVC primer allows for the creation of a robust bond that significantly extends the lifespan of the plumbing system.

Marine adhesive

Marine adhesive is a high-strength adhesive typically used in marine settings to bond and seal various materials and can be a good alternative to plumber putty.

This product comes in a tube that you can squeeze and easily apply to your sealings. It is highly effective at connecting plastics and stopping leakage.

However, it’s important to note that marine adhesives may emit strong odors and fumes. Hence, it is essential to use them in a well-ventilated area while wearing protective gear such as gloves and a respirator.

Steps to Use Alternative Sealants to Plumber’s Putty

Since a plumber’s putty is not a great sealant to work with plastics, the alternatives that we mentioned above can be used in a step-by-step process. The steps are as follows:

Step 01: Clean the Area

Before you apply any of the abovementioned alternatives, you need to clean and free the whole area using a damp cloth. Wipe down the surface and remove any dirt or grime, which will ensure strong bonding of sealant with any leakage.

Step 02: Choose the Appropriate Sealant

Based on the type of plumbing application, choose the appropriate sealant from the options mentioned above. Make sure you read the manufacturer’s instructions and select a product that’s compatible with the material you’re working with.

Step 03: Apply the Sealant

There are different ways of applying different sealant and it depends on the manufacturer’s instructions.

For example: if you go for silicone caulk, you need to apply a thin and continuous bead of caulk along the joint of the sealing. And then a smoothing tool to smooth out the bead and ensure a uniform seal.

Similarly, apply marine adhesive PVC primer according to the manufacturer’s instructions.

Step 04: Allow the Sealant to Dry

After applying the sealant, keep it dry for a few hours. Depending on the type of sealant you’re using, it may also take a full day to dry completely.

Step 05: Check for Leaks

Once the sealant is dry, switch on the water and look out for any leaks. If you notice any leaks, tighten the joints or reapply the sealant as needed.

Video on How to Apply The Alternative Sealant on Plastics

Watch this instructional Youtube tutorial to understand how to apply an alternative sealant on plastics with more visibility.


Here are some common questions people ask regarding applying plumber putty on plastics.

Q. Can plumber’s putty be safely used on other materials besides plastics?

Yes, plumber’s putty can be commonly used on other materials besides plastics, such as metals, including copper, brass, stainless steel, and iron. It forms a secure seal on these surfaces without causing damage.

Q. Do plumbers putty harden on plastic?

The purpose of applying a plumber’s putty on plastic is to create a watertight seal around sink fixtures, faucets, and drains. Hence, it’s supposed to dry on the surface to create a tight seal. So, yes, plumber putty hardens on plastics.

Q. Why is it not recommended to use plumber’s putty on plastics?

The main reason behind this recommendation is that plumber putty affects the material integrity and damages the product. Hence, you should use alternative sealants for sealing plastic materials.

Final words

Plumber’s putty has long been a go-to sealant for plumbing professionals and DIY enthusiasts alike. However, this versatile product isn’t suitable for use on all materials, particularly plastic. And now, you know why can’t you use plumbers putty on plastics.

Hence alternatives such as – silicon-based caulks, PVC primers and marine adhesives are some of the well-known products to use for leakings. Their steps of applying the alternative sealants are the same yet different from each other for which following manufacturers’ instructions is important.