Skim Coat vs. Putty. What’s The Difference?

Skim coats and putty serve similar purposes, yet they’re used differently. Skim coats tackle prominent issues on concrete, like honeycombs and waviness. Putty suits minor flaws on primed or painted walls, like hairline cracks and subtle unevenness.

When it comes to achieving the perfect wall finish, paint colour is just one piece of the puzzle. A wall free from defects and imperfections, such as cracks, dents, and holes, is equally important. This is where skim coat and putty come into play.

Sometimes, people may use the terms “skim coat” and “putty” interchangeably, but they serve different purposes. To clear up any confusion or conflict, we’ll be discussing skim coat vs putty, their functions, and applications.

Understanding Skim Coat and Putty 

A skim coat is a thin layer of joint compound or plaster used for various finishing and building tasks. Because skim coats may be used on a variety of surfaces, including masonry, plaster, drywall, or concrete, professionals prefer it.

A skim coat is used during prep work to create a smooth surface before painting or adding wallpaper. This improves the finish’s visual appeal and longevity.

Skim coatings are employed in the building sector for texture removal, wall and ceiling repairs, decorative treatments, and resurfacing. 

The product can also repair damage like small cracks, uneven texture, or dents. Skim coats can achieve a smooth or textured finish, depending on the application techniques. 

Professionals often use this versatile material to efficiently produce excellent outcomes on various projects.

On the other hand, putty is a multifunctional filler substance used in various industries, such as construction, automotive, and woodworking, to repair damage to metallic, wooden, or plastic surfaces. 

The ability to easily shape this flexible material into fissures, gaps, or holes is its not-so-secret superpower. Additionally, by generating an even, smooth surface, it helps prepare surfaces for finishing.

To increase the product’s stickiness, durability, and versatility, putty is typically constructed of polymers, gypsum, calcium carbonate, and several additives. Water-based, oil-based, and epoxy-based versions are all available.  

In discussing skim coat vs putty, both skim coat and putty are designed to address surface imperfections and defects, but their applications differ. 

A skim coat addresses more noticeable defects like honeycombs and waviness on bare concrete surfaces. It can also be used to create a smoother texture on rough or bumpy concrete. 

On the other hand, putty works best for little flaws like hairline cracks and slight unevenness that are generally present on primed or painted walls. 

Moreover, the surfaces on which they are applied vary. Skim coat is used on bare concrete and is often applied over large surface areas, such as entire walls, to correct waviness. 

In contrast, putty is applied to surfaces that have already been primed or painted and is commonly used to spot correct minor imperfections like hairline cracks. 

Regarding the painting process, if you’re using both skim coat and putty for a project, the skim coat comes first as it is applied during surface preparation, ensuring that the wall is in optimal condition before painting. 

Putty, on the other hand, is an integral part of the painting system and follows the primer application, providing a smooth, defect-free surface before the final coat of paint.

Differences Between Skim Coat and Putty

Now that we’ve discussed the specific products and their applications, it’s essential to highlight the differences between skim coats vs. putty. These variations can help you in selecting the best material for your project.

Level of Expertise

Skim coats demand a higher level of skill and precision, often requiring the expertise of professionals or advanced DIYers. 

In contrast, putty is more user-friendly (mould, sand), making it suitable for those with limited experience. It also takes much less of your time than a skim coat.

Surfaces

Given its extreme adaptability, putty can be used on various surfaces, including concrete, brickwork, plastered walls, plastics, metal, and wood. Skim coat is primarily intended for use on walls and ceilings, specifically on masonry, plaster, drywall, or concrete.

Purpose

Putty serves a broader range of purposes, extending beyond construction and finishing to include automotive and woodworking applications. The skim coat focuses more on construction and provides a heavy-duty, versatile finish.

Furthermore, compared to putty, the skim coat is significantly more resilient and appropriate for use in building. Remember that a skim coat is a robust, adaptable finish, whereas putty is mostly a filler substance for hiding defects. 

To fix a small crack, a skim coat is overkill. However, it would be ideal to use skim-coated paint when preparing surfaces on a big scale for finishing, such as walls and ceilings.

Application

In noting key differences between skim coat vs. putty, putty is easier to apply, mould, and sand, making it accessible for beginners. 

Skim coat, on the other hand, requires meticulous application in multiple thin layers using a trowel, often making it more suitable for professionals.

Moreover, there are variations in the contexts in which they are used. To address waviness, a skim coat is sprayed on bare concrete over a sizable surface area, such as the entire wall. 

It is more customary to use wall putty over smaller areas, such as when spot-repairing tiny flaws like hairline cracks on a surface that has already been painted or primed.

Another distinction between wall putty and a skim coat is how they are applied during the painting process; if both are required for a job, the skim coat is applied first. 

The skim coat, applied to bare concrete, is used during surface preparation (or before painting). The best condition of the wall can be ensured through careful surface preparation.

On the other hand, wall putty is a component of the painting method itself. Putty is the next step after applying primer to a freshly painted wall. It is utilized to inspect any remaining surface flaws. The wall is then prepared for the topcoat after spot priming.

Variety of Products

Another disparity to note when comparing skim coat vs. putty is that putty comes in epoxy-based, oil-based, and water-based formulations, offering flexibility and choices to fit your project and budget. A skim coat is typically made from joint compound or plaster, adhering to a more straightforward formula.

Affordability

Putty is generally more affordable than skim coats, both in terms of the product’s price and the quantity required for most projects. 

Skim coat is placed in numerous layers, whereas putty is applied in one layer over the broken or entire surface. Because putty is less prone to goof up than skim coat, most DIYers prefer it.

Drying Time

While both skim coat and putty need time to dry, the skim coat takes a lot longer, often requiring multiple thin layers and up to 24 hours for complete drying. Putty, on the other hand, dries in approximately four hours and can be ready for further finishing work in a shorter time frame.

However, remember that the precise time required for drying will vary based on the type of product used, the weather, and the number of layers applied. 

Putty should be left overnight for optimum results despite the fact that it typically dries in four hours. Drying for the skim coat can take anywhere from 12 to 24 hours. Using three layers could make the procedure take around three days to complete.

Sanding and Finishing

While putty and skim coats can be further prepared after their application, putty usually demands more extensive sanding and finishing work to achieve a seamless blend with the surrounding surface. 

Therefore, ensure you use what is necessary because you will likely spend much time sanding it off to achieve an even finish.

In contrast, the skim coat is applied in several layers, ensuring a uniform, smooth finish. Skim coat often does not require sanding when applied perfectly due to its multiple layers and smooth finish.

Factors to Consider When Choosing Between Skim Coat and Putty

Several factors must be considered when deciding between skim coat vs. putty for your project. Each of these materials has its unique advantages and applications. So, let’s break it down.

1. Level of Skill

Your level of expertise in DIY projects is a significant factor. If you’re not the most experienced DIY enthusiast, sticking with putty is often best. Putty is generally easier to work with and requires less finesse.

2. Financial Plan

Putty is the way to go for those working with a tight budget. It’s cost-effective, and a little goes a long way, making it a practical choice for budget-conscious individuals.

3. Work Repair

Putty excels at handling minor imperfections. A skim coat is often unnecessary if your project involves minor renovations or touch-ups. Putty can do the job efficiently.

4. Nature of the Project

On the other hand, if your project will endure heavy stress and strain over extended periods, a skim coat is the better choice. Skim coat excel in scenarios where durability is paramount.

Conclusion

Choosing between skim coat vs. putty ultimately depends on your needs and project requirements. By knowing their key differences and considering the above-listed factors, you can make an informed decision that suits your situation. 

So, whether you opt for a skim coat or putty, you can confidently embark on your project, knowing that you’ve made the right choice for your circumstances.