The first thing to understand is, seal coat (inexpensive) is a wearing surface. So also is your asphalt (expensive). You get to choose which one you’re going to abrade.
(Only one of these choices is optional. Fortunately, it’s an easy choice).
Every time your customers come in and turn their wheels, they’re abrading a very small amount of your parking lot. Some leaves on their wheels, some is swept up weekly by your sweeping vendor. Either way, someone is literally driving away with a piece of your parking lot every time they leave. At $2.00 – $3.00 a sf (original installation cost), that’s a significant investment not to properly protect and maintain.
All the more when you realize that, brand new, at 2 inches thick, asphalt can carry nearly every vehicular load imaginable, but when your parking lot is 10 years old, your asphalt is probably 1.75 inches thick (abrasion and compaction). At 15 years, it’s closer to 1.50 inches thick.
Take a good look at your asphalt. Is it smooth, or rocky? If it’s over 7 years old and hasn’t been sealed, chances are it is. Up to 25% of your parking lot may now be missing, nearly all due to abrasion. (Abrasion that can occur on something far less expensive than your asphalt).
We can’t stop aging, but we can slow it down. Seal coating helps.
When we realize that asphalt sealer is essentially tar that has been emulsified to be water soluble, and that your parking lot is made of a product (asphalt) that is nothing more than a careful mixture of sand, rock and tar…that the sun, rain and other elements have been stripping and depleting the top surface of for years, it becomes evident quickly; seal coating asphalt (replacing the lost surface tar) every 3 – 6 years is the ONLY way to keep your asphalt from decaying.
Remember the day the asphalt was placed? Jet black. Black as coal. Now, it’s gray. Yet just 1/16th of an inch below the surface it’s as black as the day it was installed. All the original tar is still inside….doing its job….but it’s no longer on the outside, where you need it, holding all these pieces of rock and sand together. That’s why your asphalt is rocky, thinner, and…breaking.
Let me be clear; seal coating your asphalt on a scheduled basis is not the “recommended way” to keep it in great condition, it’s not “a way“…it’s the only way. When we consider that repairing asphalt runs between $5.00 and $15.00 a sf, it becomes obvious fairly quickly; not seal coating your asphalt will eventually prove unbelievably expensive.
Simply put, seal coating asphalt on a scheduled basis will preserve the investment and it’s condition. It’s the only cost effective method to do so.
One more very quick point: Sand.
Do we want any in our seal coat? Yes, and No.
Years ago, sand was a prominent component of seal coat. Once upon a time in the Washington State area, we had the option of two types of seal coat; Coal Tar, and Asphalt Emulsion. Coal Tar is rigid (‘denser”…tighter molecules), Asphalt Emulsion is a softer material (more “fluid” 100% compatible with asphalt. In fact, Coal Tar is actually an additive to asphalt surfaces, Asphalt Emulsion; a “replacement…replenisher”. Think of it as an emollient).
Both are actually “emulsions” (to emulsify something essentially means to chemically or otherwise treat a liquid such that its natural solvent….in the case of tar, that would be gasoline, toluene, or similar petroleum based solvent….can be altered such that some other liquid, such as water as is the case for asphalt emulsion, becomes the “solvent” or, thinning agent. You can read more on this subject here but, suffice it to say, that’s the essence of things), however, the Washington State legislature some years back opted to make it illegal to use (Coal Tar) because it was deemed carcinogenic. It is the only State to do so, and in fact, it is the only place in all of North America to do so but, them’s the facts.
So, with that said, Coal Tar is a rigid sealer and very capably holds sand in its grip, whereas, Asphalt Emulsion is a “softer” material, directly compatible with asphalt, but it is not capable of holding on to sand, which then, if added, only comes loose, “raveling”, creating loose sand everywhere (expensive to sweep up) which is nothing more than an abrasive which will…..(here it comes)….quite efficiently wear away the seal coat we just installed for you.
(It’ll also rapidly fill up all your catch basins…not good).
So, in short, in every other state in the U.S., Canada, Puerto Rico and Guam, sand in seal coat (Coal Tar) can be a wise thing to add. It provides slip resistance and, in some cases, filler…a poor mans asphalt if you will. Not here. Not in Washington State. So, all you out of state architects, I respect your specs, and they’re probably even correct….just not here. (I don’t write the rules, I just follow them).
So…no, we do not want sand in our seal coat.
Now, with all that set aside, let’s start with the basics: The singularly most important aspect of seal coating asphalt is the prep.
Removing dirt, debris, cleaning oil stains, moss, etc. This is where every good job goes bad. I can’t say it strongly enough; prep is the most important aspect of every quality seal coat job. Cleaning with a wire broom is simply inadequate. Pressure washing to remove moss and other vegetation where it exists is the minimum requirement. Anything less, and you’ll see vegetation back, in the exact same location, in less than a few months.
The second is the quantity of material placed.
Any time you have a liquid coating, it either needs to be thinned to work well, or, it can be thinned. In either case, examples of contractors with less than desirable scruples abound. So, “how do I know if I got a quality job done?”
It’s not the millage (thickness) placed, nor even how much or how little the material has been thinned. It’s the ONE thing (when done properly) that causes complaints if there ever are any: Scuffing. Tire scuffing, to be precise.
“Hey!!! I just paid good money to have my driveway/parking lot/raceway seal coated, and now there’s scuff marks all over it???!!!”
If your parking lot does not have some scuffing from vehicular traffic within the first 10 days or so on new, freshly installed sealer (more so on commercial projects due to the size and frequency of vehicles), you essentially received black water. Seal coat so thin that it’s essentially of no economic value at all. It looks great (for a while), but in far less than 24 months, it will appear as if it had never been done at all.
Scuffing is a wonderful thing. It’s evidence that you received an appropriate amount of material placed on your asphalt, providing you with a long lasting product. If you hire us to seal coat your asphalt, be aware, when we’re done there will be scuff marks if you turn your wheels on it (even once). If you don’t want scuffing to occur on your freshly sealed asphalt, please tell everyone you know to park their vehicles a block away.
It’s gonna scuff if we do it.
“Will these scuff marks go away? Do I need to have my seal coat Vendor come out and touch those areas up?”
Yes, and No.
Yes, they will go away over a very short amount of time and, No you don’t need to have anyone touch them up, because in very short order they’ll “heal” all by themselves, blending in just fine with everything else. In a few months you won’t even notice.
Scuffing is a good thing.
Scuffing is proof you got your money’s worth. No scuffing? (Then you didn’t).
We discussed thinning the material above, and that some Vendors may thin too much. There are, interestingly, actually a few good reasons to thin the material more than manufacturer’s specs; One is if your asphalt is more than a year old, but less than four and has never been seal coated. This means it’s “dry” (“thirsty” would also be a useful verb). It’s going to “drink up” a lot of the sealer you place on the surface (first coat).
That’s a good thing; too thick, and it won’t penetrate. We want maximum penetration on the first coat. So, in nearly all newly sealed scenarios, you want it to penetrate into the pores of the surface because, the first coat tends to go “in”, the second coat goes “on”.
What I care about as a professional is how much got “in” because that’s what’s preserving your asphalt, locking in all the loose rocks and sand (and minimizing the likelihood of others coming loose). What you care about as a buyer is, how much got “on” because that’s what’s protecting your asphalt from abrasion and the elements…creating a “wearing surface”. A quality job will achieve both.
There are other scenarios where you may want asphalt sealer to be slightly thinner than normal, but none of them hold enough weight to discuss. The rest of the time you want the material to be about 75/80% as manufactured, 20/25% diluted. And you always want two coats.
There isn’t a single good reason to go with just one coat. Anyone that tells you one coat is adequate, is after your money (and your signature)….not a quality job.
Remember, the first coat goes “in”, the second coat goes “on”. Less than 2 coats is simply inadequate.
Here’s exactly how to tell how many coats of asphalt sealer your parking area needs:
1) Your asphalt need 2 coats of sealer.
2) When in doubt, see rule #1.