Exterior Foam CoatRock hard coating for all your outdoor (and indoor) foam projects!3lb bags are no longer available!!We now sell Exterior in 5lb bags. Order 2 5lb bags (select 10lbs in the dropdown) and get a discount!This stuff is super tough. It is not sandable. Has a rough stone feel when dry. It can be troweled smooth, or brushed to make a super rough finish. Can also be applied with a hopper gun. Save money when buying 25lb bulk boxes in the US!Check out our bulk listing with a fixed shipping price included: *Please note 25lb boxes ship separately from other products ordered. Orders of 20 or more 25lb boxes may ship on a pallet. For volume discount rates of 40 or more 25lb boxes, email us. For a comparison of Foam Coats, click here To see foam projects made using this product, click here Features:
  Used For:
  Instructions:Download the instruction manual here.
MIXING: Settling may occur in shipping causing a gritty texture that does not stick well. Remix if there is separation in dry mixture. Remove or break up any clumps. Use when temperatures are between 40°F (4°C) and 100°F (38°C). Mix in a clean container with clean water. Use 1 part cool water per 3 parts of powder (for example, 1 cup of water per 3 cups of powder). Add water to powder and mix until Foam Coat turns to a smooth paste. Add more powder or water as needed for your application. A drier mix is stronger. If you add Boost, a wet mix is stronger. Do not over mix. You can add powdered or water base cement pigments while mixing in the wet ingredients.
APPLYING:If using extruded foam (ie Blueboard or Pinkboard) roughen surface with coarse sandpaper. Fill big cracks and holes by applying pasty mixture with a trowel. You may add more water until mixture is thin enough to apply with a paint brush, although thinning weakens coating. Can be applied with a standard spray hopper. Use thinned mixture to texture large areas. Application time is about 40 minutes, depending on temperature and humidity. Working time can be up to 3 hours. Try smoothing or creating interesting textures. For best strength apply at least 1/4” (6mm) thick. Multiple coats may be applied. Try texturing surface before coating sets. CURE TIME: Reaches 80% of its strength in 12-24 hours, depending on temperature and humidity. Fully cures in 3-5 days. Lightly fogging the surface on and off for 24 hours will increase strength. FINISHING: Remove dust before painting or staining. This product goes on rough and is not sandable. Finish as the surface is setting up. CLEAN-UP: Clean tools and brushes with clean soapy water before coating hardens. If you add Boost, don’t leave any residue as it will be impossible to clean after it dries. WARNING: Avoid prolonged contact with skin. Wear dust, skin and eye protection. Use approved respirator when sanding. In case of eye contact, flush immediately with water, consult a physician. Wash hands with soap and water after use and before eating. Keep out of reach of children.   More Info:COMPRESSIVE STRENGTH: ASTM C109 ⚠️ California Proposition 65 Warning: This product contains crystalline silica, a chemical known to the State of California to cause cancer, birth defects, and reproductive harm. While mixing the dry ingredients use a dust mask or respirator with an RPE of 20 or 40. For more information, go to www.P65Warnings.ca.gov or HWFF's information page: California Proposition 65.   Videos:  |
Hy HWFF We have a large project that we are making plans on covering it with your exterior foam coat . This will be to large of a project to apply foam coat by hand & we would like to spray it on ! I have read you can apply foam coat with a hopper, but can not find any information on how to mix & or apply it using a spray method ? Any info on this would help greatly Thanks Jerry
Look at the Raised Beds video on the Exterior Foam Coat page. It shows the hopper gun that we use. All Purpose sprays in a similar fashion, but sets up faster than the Exterior Foam Coat.
https://hotwirefoamfactory.com/-026ECO-50-Bulk-Exterior-Foam-Coat-50lbs.html
As you will see, hopper guns spit and spatter, so smoothing with trowels and/or a tile grouting sponge is needed to accomplish a smooth surface.
I use a Marshalltown Hopper gun at the second to the largest opening. The compressor is set at 125psi and I vary the gun pressure from 40-60psi depending on the consistence of my mix. I use a fairly heavy duty 10 gallon compressor. When I've used a small pancake compressor I have to wait for it to catch up.
I want to re-coat 2 foam planters because the white finish is wearing off. Would this work for my project?
Yes, you can use our Exterior Foam Coat, but depending on what kind of foam the planters are made out of you might have to add Boost liquid fortifier. Foam Coat will stick well to polystyrene foam, the kind that has the little white bubbles, but not polyurethane which is smoother and harder and often yellowish. Boost will make the foam coat stick to almost any surface. You can first do a thin coat with Boost, then your subsequent coats without it.
Hello, I am using two part expanding polyurethane foam to cast garden sculptures rather than cement. The purpose is so clients who cannot either move or host an 800 lb piece of work can still have one in their garden. Would you recommend the Exterior Foam Coat for this? I see the Boulder Image pictures in your gallery where they have done similar work and it appears to be holding up to lots of moisture and use. Any tips on getting it sticky enough for this type of foam or will mixing it with Boost be enough? The problem is that this foam is glossy and doesn't have much 'tooth'.
Hi Ron,
People who have been using the two part expanding polyurethane foams like Great Stuff can't get our coatings to stick. Probably because they are waterproof. Several customers have recently tried adding Boost to All Purpose and to Exterior Foam Coat with one reporting back that they adhered well. I can't vouch for this as I haven't tried it myself.
Note that subsequent layers should not need Boost. If you go thicker than 1/8" with Boost you could get some surface fissures. We have applied up to 1/2 thick layers of straight Exterior Foam Coat with no cracking.
One of the most difficult parts of coating foam is getting the first layer to leave the brush to go onto the foam, so yes, hopper-spraying at least the first coat on to give some 'tooth' to the next layer is a smart technique. Pancake batter thickness seems to work well in our hopper gun.
We, and many of our customers, have made boulders out of EPS foam, but each needs to be carved.
If you would like to send some scraps of this foam to us we will do some testing:
Hot Wire Foam Factory
Product Testing/Dave
216 East Laurel Ave
Lompoc, CA 93436
How long do I need to wait between layers of all purpose foam coat and a second layer of foam coat or paint, and how much longer would the drying time be for the exterior foam coat? Thank you for using our shopping system
Hi Patricia,
You can apply subsequent layers up to 3/8" thick of All Purpose Foam Coat in about one hour increments. For painting, wait until the last coating no longer feels cold to the touch and when it loses its darker/wet look, usually in 2-3 hours.
The Exterior Foam Coat applied in1/8" to 1/4" thick layers will be dry enough for subsequent layers in 6-12 hours, depending on how hot and dry the atmosphere is. You can apply subsequent layers as soon as it sets up, usually in 1-2 hours, but applying this soon will increase the overall drying time. For painting, follow the same instructions as for the All Purpose, but it will be quite a bit longer, probably 6-12 hours.
Note that if you apply either foam coat with a hopper gun you can keep applying thin layer after thin layer until it starts slumping (see the video on our YouTube Channel: Exterior Foam Coat Applied With Hopper Gun. It will dry much faster when applied with a hopper gun.
It's always a good idea to play around with some small batches until you find the procedure that best suits your needs. Victoria, who teaches foam coating, tells her students that once they've made a couple of batches it will feel simpler than cooking a batch of pre-mixed cookies.
Let us know if you have any further questions,
I am using polystyrene foam to create a slate look background like this one on YouTube-
He is using All Purpose Foam Coat in his video. It is easier to apply and dries faster than the Exterior Foam Coat, but the Exterior is stronger and looks and feels more like real stone than the All Purpose and will have enough texture for your lizard to climb on.
Thinning down a lot will weaken both of the coatings. It's better to exaggerate your details an put it on thicker. You can create a lot of your detail in the foam coat as it dries. Check out the Foam Gone Wild DVD.
We have a foam-coat/stain system that is aquarium safe and will produce a beautiful natural stone or reef look. Exterior Foam Coat is applied over the foam shape. The coating is then sealed with Stainfast, which is also a base for water-base stains. Stainfast does not have NSF approval because it is not a coating. It seals on a molecular level. It is a densifier which prevents water from passing through after the chemical conversion. Stainfast was used to seal sea life exhibits at Sea World in San Diego.
Lots more information on using Foam Coat in aquariums and reptile enclosures here:
http://gallery.hotwirefoamfactory.com/faqs/faqs-gluing-and-coating/
And examples with images here:
http://gallery.hotwirefoamfactory.com/gallery/habitats/
Lots of good options!
How durable would Exterior Foam Coat be outside with wind and rain snow direct sun and wide temperature changes from +90 to -40? I plan on using the Pink foam board 4x8 sheets and carving my own Stone Faux Pannels to future on the bottom of my porch and house, we have a lot of wind rain and snow and hot sun and sub zero temperature.
The Exterior Foam Coat is made to hold up in all weather conditions. It will easily withstand the hottest climate conditions, and although low temperatures will not damage Exterior Foam Coat a combination of moisture and freezing temperatures can. Our product is similar, though stronger and stays adhered to foam much better than stucco, but will react the same to extreme weather conditions. Here is an article that will give you some good parameters for your project:
http://www.ehow.com/how-does_4760049_stucco-exterior-fare-winter-climates.html
Exterior Foam Coat is denser and less permeable than stucco, so should work somewhat better in moist freezing conditions than stucco does. Do any homes in your area have stucco finishes? Have you noticed a breakdown of the stucco where it is not sealed with paint?