When it comes to navigating the world of coated abrasives, there are many variables to consider, and it can be complicated to identify the best solution to meet your needs. In part 1 of this two-part series, we covered an overview of the technical aspects of abrasives to give you a primer of what the world of abrasives has to offer. If you haven’t looked that over or are unfamiliar with these aspects of coated abrasives, you’ll want to read that before moving forward.
In this second part, we cover a framework for applying the technical aspects to choose products that will work best for your particular needs. This article also includes a matrix of a sampling of popular applications and recommendations for them.
Part 2: Understanding your application
Once we understand all the technical components of abrasives, the next step is to consider the particular application. The following are some specific topics to address in the selection process:
- the material and qualities of your workpiece;
- the specific sanding application;
- the techniques you’ll be using;
- the possible issues you could face;
- your values/priorities in product selection and sanding.
What type of material are you sanding?
One of the most important factors to consider when choosing the proper coated abrasive product for your needs is the material you’ll be sanding. This is because every material has different physical properties that will influence factors, such as the tendency to load faster, the need for more or less pressure when sanding, the hardness of the material, and how that will affect the grain’s friability appropriateness for wet sanding and so forth.
In general, the goal with sanding is to produce the least amount of heat possible. Doing so will result in a better finish and a longer lifespan for your abrasives and, therefore, a lower cost for supplies. Knowing the properties of the material will help you optimize this.
When we discuss the softness/hardness of a material we’re sanding, we are discussing the susceptibility to heat/melting, as the friction from sanding will generate heat. This heat will then cause the resins in woods, paint/finishing products, and glue to melt and become gummy/sticky and stay on the sandpaper, along with the sanding dust and any other stray particles.
For this reason, when sanding these materials, it can be helpful to choose products that would have a semi-open or open coat, stearation, and the proper grain type for the application/material. However, if you’re in the finishing stages, a closed coat will produce the most even scratch, so you may want to consider that, depending on your goals. For instance, if you’re painting the surface, the scratch will be less evident than if you’re using stain on wood.
What type of sanding?
Sanding comes in many forms, as discussed previously. If you already have your sanding system set up, this will likely be the easiest part of determining what you need as it will be dictated by the parameters of the machine you use or whether you’re hand-sanding.
There are many machine sanders out there. Following is a brief discussion of just a few of those types, but others exist for specialty niches, such as floor refinishing, moulding sanders, and brush sanders.
Machine Sanding – Belts & Drums
Generally, using belt and drum sanders will be more efficient than hand sanding; however, there is a higher upfront investment. This should translate to much more saved time and higher output rate and balance out in the end. It’s best to use this sander style when you have large, flatter items to sand—for leveling, and sometimes even finishing grits can be run through these machines.
When determining what belts or rolls to purchase for your machines, the first noticeable factor is the size dictated by the machine. However, it’s also essential to consider the belt joint style and how many sanding heads are in the machine.
Additionally, the other aspects will be based on the specific applications and removal rate you’re looking to achieve, such as grit sequence and backing of the belt. Regarding the backing, we generally recommend paper belts, unless cloth is needed for heavy-duty, very rough sanding or the flexibility of softer cloths for things like mouldings and profiles.
Machine Sanding – (Random) Orbital Sanders
Random orbital sanders are great time-saving tools when you have a lot of finishing work or are on the go, such as working on job sites as contractors or in a stationary woodworking facility. They also offer a great opportunity in automotive refinishing, where sanding can take days to get through the grits and various processes.
Using a random orbital sander helps speed up the process, as opposed to hand sanding. Using a sander like the Ekasand, as opposed to other varieties, which are often much larger and bulkier, allows for less vibration. This more ergonomic design is easier to handle, and, ultimately, a very good finish.
If you’re sanding larger spaces, using a 6”, 3×8” or 3 2/3 x 7” version will save the most time, whereas if you’re sanding in smaller areas, the 3”, 5”, or 3×4” will be a good fit. If you’re sanding inside areas where there are 90-degree angles, try the rectangular version, as you’ll be able to sand right to the corner. When using the rectangle Ekasand sanders, we recommend using a pad saver to minimize swirls that result from the vibration and non-random oscillation.
Hand Sanding
While hand sanding will undoubtedly provide a less costly option, since you’ll not need to purchase machines, it will be more labor-intensive, thus, possibly costing more in the end.
Furthermore, hand sanding can produce inconsistent results, as you may use more or less pressure or press harder with one finger over another. These things can cause an uneven finish.
Hand sanding can be done with sheets cut or folded or with sponges. When using sheets, it’s recommended to apply them to a block of some sort to have a more sturdy and even surface.
When using just your fingers, we offer a 3×4” sanding block with a hook and loop face that works well with our 3×4 hook and loop sanding sheets, 3×4” interface pads, and 3×4” Ekasilk Plus sponges. We also offer several different types of sanding sponges. The specific application will determine which would best suit your needs.
What is your sanding application?
In addition to the other parameters above, understanding your application is critical for selecting not only the proper grits/grit sequence but can also influence other factors, such as the grain type, backing, and which style of sanding (machine or hand) and so on.
Rough Sanding Applications
Rough sanding applications, such as sanding down edges on furniture, will typically require a heavy-duty product with a sturdier backing, such as cloth or a heavier weight paper.
Film products also offer a durable backing option; however, this won’t apply if this process is happening in a belt sander. Rough sanding applications will typically require lower grits, 80 and lower, and more aggressive sanding action, such as in a belt sander.
As for the grain selection, choosing a product with aluminum oxide may be a good option if sanding wood, though with raw wood, you might select zirconia for milling applications.
Medium Sanding Applications
Medium sanding applications would include final shaping and removing marks from previous sanding applications and preparation for finish. These applications would typically range from about 80-150 grit. Choose a film, paper discs, or sheets for your orbital sander or lathe, or a sponge product for hand sanding on finer things.
Fine Sanding Applications
Fine sanding includes applications such as sanding between coats of finish and polishing. This includes both wet and dry sanding applications. Generally, fine sanding is in grits 180 and finer. Both aluminum oxide and silicon carbide are used in finishing applications.
If you’re looking for a little more of a cut, but your surface has contours, you may want to try a 3×4 sander with an interface pad with our Filmtek. This can give you the cut-rate you need while helping to match the surface and absorbing some of the vibrations from the sander, preventing damage.
Depending on the circumstances, we generally recommend using a flocked-back, foam product, such as our Ekasilk Plus sponges, on an orbital sander, as they’re long-lasting and will speed up the finishing process. If you’re wet sanding, make sure the product is waterproof, such as our Ekawet paper.
A lot of finer sanding is also done by hand, so we have hand sponges and sanding blocks with hook and loop faces that provide a surface onto which you can mount 3×4 sheets of standard coated abrasives if using a sander isn’t for you.
When it comes to sponges, there are different types of foam and different thicknesses, all of which can be used for various projects. Generally, harder foam is better for flat surfaces, and softer is meant for matching contours. Our Ekadiamond sponges have a special coating/pattern to help reduce loading, which provides a great option while finishing.
What issues are you trying to prevent or repair?
No matter what stage you’re at with your project, you can encounter predictable problems. Whether that be static, chatter, broken belts, swirls or torn discs, dust, loading, moulder knife marks, all these issues can be either prevented, reduced, or repaired with the proper selection of products.
Dust, Loading, & Static
If your abrasives are loading excessively, there could be several issues. Some things to try would be to use a product with an open or semi-open coat, wet sanding (in higher grits), or a stearated product.
If static is the problem, try a product with a stearated coating as this can help reduce friction. If dust is the problem, when using a random orbit sander, choose an option with dust extraction.
Wide Belt Sanding Issues
Suppose you’re experiencing chatter or issues with excessive loading on the wide belt sander. In that case, the belt joint could be an issue, so check out this article discussing the various belt joint styles and their advantages and disadvantages to see if you might be better served with another style.
Orbital Sander Issues and Swirls
These are one of the most annoying issues seen with orbital sanding when it comes to swirls. If you need to mask them use our maroon Uneelon non-woven pads on a 3×4 orbital sander for heavier swirl marks, or our grey Uneelon non-woven pads for lighter swirl marks.
It’s not recommended to try this application with the 5” non-woven discs for this application, as the random orbit on the disc sander can cause more swirls; therefore, the 3 x 4 must be used to get rid of swirls effectively. These will mask them enough that they are no longer seen in the finish.
Moulder Marks
Our Ekasilk sanding sponges can be used to remove light moulder marks. If they’re deep, we recommend trying a 3×4 sander with interface pad and Filmtek.
What are your goals for the project?
A fundamental issue to consider when determining what process to follow in sanding and what products to use is determining your priorities for the project. Are you looking to get the best finish or spend less time or money on the project? What’s the budget? These are important questions because if your goal is to save money, you might do that by choosing less expensive products.
Or you might see value in using more expensive products because they’ll last longer and you won’t have to throw them out so quickly, thereby saving money. Additionally, using certain products and techniques may be more efficient, saving on labour and other costs, but may have a higher upfront investment.
If you’re looking for the best finish, it’s often best to use machine sanding, as that will typically provide a more consistent scratch, leading to a better finish. Additionally, if the best finish is more important, using products designed for finishing at the right stage will also be helpful, rather than simply getting a finer grit of the regular coated abrasive. Using Ekasilk Plus, designed for finishing, will help save time and help avoid problems like cut-through.
Sanding is usually the least exciting part of the project; however, it can often be the most time-consuming and potentially frustrating. However, when you have the right product for the job, it can make the process more efficient and produce better results.