Exterior Foam Coat #026


$9.95


SKU: 026
Weight: 3.00 lbs
Application Time: 40 Min
Working Time: 3 Hours
Cure Time: 5 Days
Finish: Strong/Hard
Resistance: Weather Resistant

Size:
Quantity

Exterior Foam Coat

Rock hard coating for all your outdoor (and indoor) foam projects!

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:

  • Adheres to polystyrene foams

  • Forms a weather-resistant surface

  • Use above or below grade

  • Apply with a paintbrush, trowel or hopper gun

  • Paintable

  • Fireproof

  • Many decorative surface textures can be created

  • Soap and water clean-up

  • Add Boost fortifier if extra strength is desired. (will not work with Bounce)

  • Made in USA

 

Used For:

  • Coating Styrofoam, white beaded EPS, and extruded XPS foam

  • Adding strength, texture and a weather and fire-resistant surface

  • Theatrical and studio props and backdrops

  • Holiday props, like Halloween tombstones and yard props

  • Garden décor, like fake boulders and waterfalls

 


Instructions:

Download the instruction manual here.

Coverage
Thickness: 1/64" 1/16" 1/4"
3lbs: 36 sq ft 9 sq ft 2.25 sq ft
25lbs: 288 sq ft 72 sq ft 18 sq ft

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.

Mixing Chart
Create Coat Water or Boost
3 Parts (by volume): 1 Part
3lbs: 1 Cup/8oz (Makes slightly dry mix)
25lbs: ½ Gallon/64oz (Makes slightly dry mix)
50lbs: 1 Gallon/128oz (Makes slightly dry mix)

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. For best strength apply at least 1/4” (6mm) thick. Multiple coats may be applied. Try texturing surface before coating sets.

CURE TIME: Working time of 1.5-3 hours. 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
1 Day 750 psi
7 Day 2500 psi
28 Day 3500 psi

FLEXURAL STRENGTH: ASTM C348
1 Day 350 psi
7 Day 550 psi
28 Day 1250 psi

FIRE DATA:
Flammability: Noncombustible and not explosive.
Auto-ignition Temperature: Not Applicable
Flash Points: Not Applicable

Click here for Foam Coating and Gluing FAQs

WARRANTY: HWFF Inc./dba Hot Wire Foam Factory warrants this product to be of merchantable quality when used or applied in accordance with the instructions herein. The product is not warranted as suitable for any purpose or use other than the general purpose for which it is intended. Liability under this warranty is limited to the replacement of its product (as purchased) found to be defective, or at the shipping companies’ option, to refund the purchase price. In the event of a claim under this warranty, notice must be given to The Hot Wire Foam Factory in writing. This limited warranty is issued and accepted in lieu of all other express warranties and expressly excludes liability for consequential damages. MSDS available.

⚠️ 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?


Im fixing a lodge made of 100 year old logs. Some corners are rotting. I need to replace damaged wood . But I can not cut to the inside. The logs are 8 in thick. I cut in about 4 inches then remove all the bad wood. I was hoping that i could use your product with foam to create a repair that would be weather proof and wood like. Craig Erickson
This type of restoration is commonly accomplished with our tools. Our Exterior Foam Coat is super strong and weatherproof. Our latest formula is made to be slow drying so you will have plenty of time to shape the surface to look like grain or bark. Paste the following link in your browser to see an example. All of the wood in this zoo is a combination of real wood, and foam plus foam coat. http://gallery.hotwirefoamfactory.com/gallery/habitats/hab_mrichard3/

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Customer Reviews

Bobby Harpoon, 11-26-2016

This is a great product for increasing the streangth of the surface of your prodcts. I was amazed by how tough it dried. There are vidieos on how to create texture on the outer surfaces with this product. The one draw back that I have found. Is clearly stated in their own product descrption. "This product goes on rough and is not sandable. Finish as the surface is setting up." When I left some high ridges or spikes where the adhesion properties made it create a high draw point when lifting the application tool. It was very difficult to remove when dried. Best to make the finish as needed while applying product. It does make the surface tough which is the high light to this product.


Tina Padziora, 12-31-2016

OMG. No more plaster use for my projects!! This exterior foam coat is awesome. I tested it by applying it to my styrofoam then blasted it with a high pressure water hose (apx 20 feet from target) then for kicks I took a sand blaster (apx 30 feet from target) to it so I could see what weather would do. Not 1 dent, scrape, or puncture anywhere. This stuff dries really fast and is really hard as rock when dry. If you want a product that will give you a stable long lasting finished project this is what you need. And NO I do not work for this company. But I will be buying stock if it is available!


Terese Agnew, 11-03-2016

I love this stuff! I'm currently working on a very large sculptural installation called Writing in Stone that is traveling through the state of Wisconsin with some truly amazing history. Since it has to travel--it couldn't be as heavy as real stone! The look and feel of stone coat has been so convincing and wonderful to work with.....galleries have had to accept that people can't stop touching it. A okay with me! You guys rock.....seriously--always helpful answering questions and the product is not only terrific--it's fun to work with. Also--again--no FUMES! but do wear a mask for mixing the powder. I am also very happy to know that this is a family-produced US product.


Scott Aldrich, 02-22-2017

I build Vivarium Hardscapes and use this product to provide a rock like feel and appearance, it also provides much needed strength.


Bruce Lee 007, 07-07-2017

FYI,
Exterior Foamcoat is very good stuff. It was easy to apply on the styrofoam and it didn't dry quick until I applied it on the sandfall. The hybrid or quick settings cement gave me so much problem in the past.
They dried out too quick and thin layers were not strong and chipped off.
Foamcoat is at least 7 times better than the cement based on my experience.


Tammy Jeffres, 11-22-2017

Exterior foam coat is so easy to use for vivarium scapes and so easy for clean ups. Low odor too. Exaggerate your sculpting on foam piece, apply thin layers of EXFC and finish last coat with your texturing or for rock faces, ridges and the top line of a crevice. Goes on sandy and dries fast. Can be easily painted. Friends have said they thought my rocks were real, but I can sculpt pump and fan housings into the foam and use less weight making my own. Be sure you clean up immediately bc this stuff becomes rock hard and permanent. Not recommended in my opinion for tree scaping bc of sandy finish.


Logan Sharpe, 07-11-2018

Was very easy use and cleaned up really nice. Would use again!!!


Eric Claeys, 10-21-2018

This is nothing but fine grit tile mortar/grout, sold in a small can. The mixture contains a lot of air - after adding water, it bubbles as the air escapes and your 4 cups becomes 2 cups (3 mix + 1 water). 3lbs wasn't enough to coat 1 medium sculpture ( roughly 2x2' ft) and the 3:1 ratio is extremely thin/watery. Would not recommend this product.


Carol Willett, 12-02-2018

In sculpting an outdoor garden snail covered in mosaic tiles and glass gems, I found the exterior foam coat an ideal prep material. It sealed my foam sculpture and gave the surface good tooth for application of concrete and tile setting adhesive. The snail looks great and has stood up well to our difficult seaside weather.


Angelina Ellis, 03-12-2019

This is a great weatherproof sealer for outdoor foam projects. I used to coat a mardi gras float before spray painting it with an acryllic paint and then handpainting details. It is a bit gritty like stucco, and I was worried the grit would shed after it was dry, but it didn't budge.


Roman Gluhov, 04-11-2019

Great new coat, recommend it!


Jonathan Singer, 12-06-2021

So, my 3 pound container of exterior foam coat arrived today. I had to crack the white top in three places just to get it off. The problem was that some of the gritty powder was left on the threads when the top was put on. When that happens the top is basically locked on and can't be unscrewed.


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