When you consider floor coatings you need to do a little math about the amount of “solids” in the liquid coating you buy. If you buy a coating is chemically 100% solids, what you pay for is what you’ll end up with. BUT if the product is only 50% solids material... 1/2 of it is going to evaporate! In other words, even if a 100% solids coating cost twice as much as a 50% solids coating in the end you’ll come out exactly the same, because it takes 2 gallons of 50% solids to coat your floor with the same depth of protective coating!
How does that work? Here’s the key… One gallon of ANY paint (or even ANY liquid) will cover 1604 square feet to a depth of 1 mil. That means, if you spread ONE gallon of water on a surface at 1 mil thick you would cover 1604 square feet. If you spread one gallon of paint at one mil on the same surface you will cover... 1604 square feet. How many square feet will a gallon of milk, root beer, or even crocodile tears cover at 1 mil thickness? You guessed it... 1604 square feet!
Of course that’s when the liquid is wet - now, let's move on to what happens when the liquid dries. If the coating is any bit less than 100% solids the thickness will decrease because any additive or extender that is not a solid must evaporate or “outgas.” Many floor epoxies and other coatings have water or (as in your case) solvents added to them, and neither of them are solids. Spread one gallon of either water or a solvent and it will initially cover 1,604 square feet to a depth of 1 mil, but in a short time how thick will that coating be? That’s right – zero mil thick; because both will completely evaporate.
How does one figure out how thick a final coat will be? Easy… take the same calculation from above and then multiply by the percentage of solids of that material.
100% Solids will (still) cover 1604 Square feet per mil per gallon when dry (1604*100%= 1604)
90% Solids will cover 1443.6 Square feet per mil per gallon when dry (1604*90%= 1443.6)
80% Solids will cover 1283.2 Square feet per mil per gallon when dry (1604*80%= 1283.2)
70% Solids will cover 1122.8 Square feet per mil per gallon when dry (1604*70%= 1122.8)
60% Solids will cover 962.4 Square feet per mil per gallon when dry (1604*60%= 962.4)
50% Solids will cover 802 Square feet per mil per gallon when dry (1604*50%= 802)
40% Solids will cover 641.6 Square feet per mil per gallon when dry (1604*40%= 641.6)
30% Solids will cover 481.2 Square feet per mil per gallon when dry (1604*30%= 481.2)
20% Solids will cover 320.8 Square feet per mil per gallon when dry (1604*20%= 320.8)
10% Solids will cover 160.4 Square feet per mil per gallon when dry (1604*10%= 160.4)
0% Solids will cover 0 Square feet per mil per gallon when dry (1604*0%= 0)
So, not only will the coverage of an identical size area be thicker with 100% solids, it's less gallons to spread. As you can see you can spend double the per gallon cost of a 50% solids material and still come out ahead because it’s less work.
Given you have 480 ft2, and knowing the coating isn't 100% solids, the questions for you are - what wet or dry depth does your manufacturer recommend, and what % solids is your epoxy? Both bits of info should be found in the instructions, product data sheet, or maybe MSDS.
