When looking in the dictionary, the meaning of the word caulk is “to fill or close seams or crevices to make watertight, airtight, etc.”
Caulk, often called sealant today, comes in several forms, but all are either sanded or unsanded. Both are used to seal a joint between two materials.
Apart from the added sand, the other big difference is that unsanded caulk is highly flexible.
A caulked joint is watertight, dust-free, and stops pesky critters from invading your home.
Caulk is one of the most valuable and versatile materials. Like most materials, using the correct one in the proper application will ensure that your job has a professional finish and will only have to be done once.
If you have seen that some varieties of caulk have sand added and are unsure when or where to use it, this is your chance to find out.
What Is Sanded Caulk?
So, here’s the scoop. Sanded caulk is simply what we think of as an ordinary caulk but with sand added, which gives it extra bulk and strength.
The addition of sand prevents the caulk from shrinking as it dries, but it’ll appear rougher in texture.
Where Do I Use It?
The addition of sand helps prevent shrinkage as it dries, so this type of caulk is advantageous when tackling relatively large gaps.
By rather large, I’m referring to any space wider than 1/4″, but often larger.
It can be used on drywall, tiles, stone, wood, and any other surface where shrinking of unsanded caulk would cause problems.
Next let’s talk about where you don’t want to use it.
Where Don’t I Use It?
Sanded caulk isn’t very flexible, making it more prone to cracking if used in places where the two surfaces are inclined to move against one another.
For this reason, it isn’t a good idea to use it around areas where you want the caulk to flex, for example, around the rim of the bathtub or in sealing a shower stall.
What Tools Do I Need?
You’ll need the tubes of caulk as well as a caulking gun. Look for a good quality drip-free gun. This should cost around $10.
To help you choose, watch this short video:
If your caulk is water-based, you can clean up and smooth it out using a damp cloth, your finger, or a caulking tool.
Also, a small amount of water mixed with dishwashing liquid and some rags will come in handy.
If your caulk needs mineral spirits or thinners for cleaning up, then you’ll need mineral spirits or thinners and rags.
Physical Properties of Sanded Caulk vs Unsanded Caulk
Ceramic tile sanded caulk being applied – See Product from the Home Depot
Caulk or sealants require many physical properties to ensure that they can do the job. Let’s look at some of the properties of caulk and how adding sand may affect them.
Caulk used in vertical joints should have a thick consistency that won’t snag or run. This is true of sanded caulk, where the texture will be much thicker than the unsanded variety.
The expected life of a sealant under laboratory or ideal conditions isn’t anywhere close to its actual life in the real world.
Under ideal conditions, silicone sealants generally can be expected to last around 20 years, while an acrylic caulk is unlikely to last more than five years.
Adding sand to the caulk will help ensure the caulk survives when applied to large gaps, as the sand will add bulk that helps with shrinkage.
Hardness and flexibility are opposing forces in caulk. If you need a caulk with great flexibility, it can’t be hard, and vice versa.
If you’re going to seal a joint in an area where it’ll be subject to scuffing or other damage, then the product’s hardness is essential. The hardness will prevent damage to the seal if it’s subjected to wear and tear.
The inclusion of sand in a hard caulk will ensure that the caulk isn’t easily damaged.
Sealants that are to be used in an area where they’re exposed to the elements require a degree of resistance to exposure.
This resistance may be against UV rays, heat, or moisture, and there are sealants designed to do these tasks.
In any of these sealants, the addition of sand won’t make any difference to their ability to withstand the sun’s rays, moisture, or heat.
In these high-performance sealants, the resistance comes from the chemical composition of the caulk.
The ability of caulk to expand and contract is essential in many applications. This movement capability is often expressed as a percentage.
This means that the sealant should be able to expand and contract to the stated percentage.
So if the stated movement capability is 10% and the joint is 15mm wide, then the sealant should be able to expand to 16.5mm or contract to 13.5mm and not fail.
Sand would be added to caulk used in places with a low movement capability as the sand would decrease the caulk’s ability to move.
Modulus of elasticity is the ability of the caulk to resist being elastically deformed when stress is applied to it.
Caulk with a high modulus of elasticity is used in static joints where little or no movement is expected.
An example of this would be on a baseboard or crown molding. Adding sand to this type of caulk will assist with increasing the modulus of elasticity.
This is one of the most essential characteristics of any caulking product. In the case of sanded caulk, the addition of sand will make no difference to the product’s ability to adhere.
The chemical properties in some sealants can leach into porous materials. This can leave a stain around the joint.
Any caulking product that is to be used on a porous substrate, such as natural stone, should be tested first to ensure the chemicals won’t leave an unsightly stain.
Again, adding sand will have no effect on the chemicals leaching out of the caulk.
Ease of Application
Some sealants are very easy to apply and to get a nice smooth finish. These are most often water-based products.
When comparing sanded vs unsanded caulk, smoothing out is the same in that once you’ve applied the bead, you can use a wet finger or damp cloth to get a smooth finish.
Sand will affect the look of the caulk when it’s applied. Sand will naturally give a rougher finish that may not be appropriate in high visibility areas.
Cheap caulk may end up being expensive at the end of the day. Buying and using cheap caulk can result in poor finishes that don’t last.
Ensure that the tube you take off the shelf is for the materials you want to join and that it has the right degree of flex.
Sand isn’t a consideration in terms of cost. Top-quality caulk is more critical, along with buying the right caulk for the job.
Can I Paint Sanded Caulking?
Not all caulks can be painted. Ensure you read the tube and make sure it states that it’s paintable before you buy it.
Can I Sand it?
Sanding caulk can spoil the surface, and while this isn’t so evident on sanded caulk, it can still ruin the look of your finished job.
Instead, spend time applying the caulk correctly and ensuring a neat, clean finish that’ll be almost invisible when painted.
Should I Seal it?
No, this isn’t necessary. The only difference between sanded and unsanded caulk is the addition of sand, so it doesn’t need to be sealed.
In fact, over time, the chemicals in sealants may damage your caulk. If you have to seal tiles and grout, do that first and, when it’s dry, then undertake your caulking.
What Are Sanded Silicone Caulk, Sanded Grout Caulk, and Sanded Ceramic Tile Caulk?
Sanded silicone caulk would be used to seal plumbing fixtures in a bathroom, kitchen, or laundry. It’s also suitable for sealing windows and doors or where cables enter your home from the outside.
Remember that as it has sand added, it won’t be as flexible, so restrict it to areas where you don’t expect much movement.
Sanded grout-caulk is used to fill the joint where two tiled surfaces meet.
The color of this product will exactly match the grout used in laying the tiles, so the joint won’t be apparent.
Sanded ceramic tile caulk is used to fill in the joints where two surfaces covered with ceramic tiles meet, and a small amount of flex is required at the joint.
Sand can be added to almost any kind of caulk. It adds strength and bulk to the product and fills significant gaps between any two surfaces.
It isn’t as flexible as other caulk products, so it shouldn’t be used in places needing flexibility.
It comes in a range of colors, won’t shrink excessively, and some types can be sanded and painted.