How to Get the Most Out of a Spray Foam Kit
As you know, the number of a Foam it Green kit corresponds to how many board feet it can cover when used correctly under optimal conditions. So, the Foam it Green 602 can cover 602 board feet, or 602 squared feet at a cured thickness of one inch, 300 squared feet at a thickness of two inches, and so on. But, how can the operator help make sure the kit gets as close to that number as possible?
Tip #1 – Component Temperature
To create good foam that is on-ratio, meaning as close to 1:1, A:B, as possible, the tanks need to expel the components in them at the same rate. While there is propellant in each tank, the actual rate at which the components are forced out is dictated by the temperature of the materials inside. Notice, we’re referring specifically to the temperature of the materials inside the tanks, not the surface temperature of the tanks. If you have stored tanks in a cool environment, they should be brought up to ideal operating temperature in a warmer area, shaking them periodically to redistribute the internal temperature of the materials. Components can be used between 65-85F degrees but the best results (ideal conditions for maximum coverage) occur at 75F. If you only warm up the tank surface, and the components inside remain cold, then an off-ratio spray can occur which does not let the foam set up correctly and costs coverage. The great news is that Foam it Green makes it easy to see that you are getting the right mix because the blue and yellow components will then spray green!
Tip #2 – Surface Temperature
Foam it Green will bond to surfaces that are dry and clean if they are 65-85F degrees. You may notice when spraying that the foam heats up when the two components come together and it begins to rise. This exothermic reaction causes the foam to expand to the correct thickness and density, which in turn gives the desired R value. So, if the surface to which you are spraying is too hot, more heat is added to the reaction which can cause a premature cure that does not expand fully – this can cost coverage. Alternatively, too cold a surface steals away precious heat that the foam needs to expand, again causing less expansion, and costing coverage. Spraying a surface that is too cold can also shock the foam causing it to pull away and not bond to the surface. Ideal surface temperature is 75F degrees.
Tip #3 – Spray Thickness
As you can see by now temperature has a great deal to do with proper operation of a kit as well as how much you’ll get out of it. Spray thickness directly impacts the foam’s temperature, so it is equally as important as tank and surface temperature. With Foam it Green closed cell formula, a target application thickness of 1/3 (one-third) of an inch is ideal. This amount will allow the two components to heat up to the optimal temperature for it to rise and cure to one inch. If you are looking to ultimately have cured foam that is 2 or 3 inches thick, then you should spray a third of an inch, let it expand to one inch, and then when the foam cools (remember, surface temp is important!) spray another third of an inch to rise to one inch and so on. Attempting to end up with 2” of closed cell foam in a single spray would mean putting the foam on thicker, adding more heat to the exothermic reaction, faster curing, and less expansion/coverage. Foam it Green open cell formula is a little different so it’s best to apply it about a half inch wet so that it can rise to 2”. It’s not recommended to try to get 1” cured open cell foam per pass.
Tip #4 – Stop if it’s Not Green
Foam it Green is designed to alert the user right away if the spray is not on-ratio to avoid wasting it. More often than not, if it is not on-ratio, it will be blue in color. That’s because having too cold or too warm components produces a similar issue for slightly different reasons. If your tanks and components are too cold, the yellow A component will likely expel at a lower than desired rate. With less yellow A to match up with blue B coming out, the foam can spray blue and not expand or cure. Alternatively, when the tanks are both too warm, the blue B can spray faster than desired which again, even with the yellow A running at a proper rate, can spray blue, not set up, expand, and cure. That’s why there is a sweet spot of 75F throughout the materials in the tanks. Essentially, having tanks that are too cold or too warm can spray blue in both cases. Depending on where you are and how the kit was stored, getting on the right track usually means either heating the A component or cooling down the B component. You may notice that you have leftover blue B component at the end of a kit. This is normal and it should be disposed of in accordance with the instructions. Last note about pressure: the propellant that is added to the tanks has weight, and all tanks are weighed multiple times on their way to your project. That means that tanks that are underfilled or missing propellant in the manufacturing process are not the cause of an off-ratio spray. Moreover, a propellant leak due to tank damage doesn’t “weaken” pressure, it removes it. That means that propellant escaping does not cause a slightly off-ratio spray, it means that the tank would likely not even be able to push component into the hose.
Tip #5 – Change Nozzles
If you stop the flow of foam through a nozzle, it will cure just like it does on the surface you intend on spraying. So, any time you stop for 30 seconds or longer, change out the mixing nozzle. Mixing nozzles cannot be cleaned out and re-used, even with acetone, so consider buying additional packs of them if your project requires a lot of stopping and repositioning. Also, if you happen to be spraying and notice a change in spray rate or direction, change out the mixing nozzle as continuous spraying for an extended period of time can also clog up the nozzle.
- You can store tanks between 40-100F degrees, but most folks find it easier to store them at the correct operating temperature so you don’t have to spend additional project time heating or cooling.
- Store your kits somewhere dry so that rain water or condensation doesn’t corrode the tanks.
- Tanks won’t spray correctly on their sides, so keep them in their boxes standing straight up when spraying.
- If you plan on stopping before you use up a whole kit, keep the hoses on the tanks, remove the mixing nozzle from the gun, cover the face of the gun with petroleum jelly, and turn off the tanks.
- When spraying, cover any exposed skin along with anything else you do not want foam permanently on. Wear gloves, goggles, and a particulate respirator with a p100 filter for organic vapor and acid gases.