Foam Core Construction –
What You Need to Start for Vertical Decorative Concrete
By Nathan Giffin of Vertical Artisans
When considering this field or form of construction there are a few things that really need to be in place. The tools required to assist you in the production of a foam core project are really quite different than most of the tools you may have already purchased.
Let’s start out by defining the types of tools you will need.
Transformers
These are a variable power source that we use to cut the foam.
Variable because depending on the length of the wire we are using directly correlates to how much power or heat is required. Most transformers will generate enough power to literally melt the wire right off the tool so caution must be used when working with these types of tools. Because the transformers have variable power, this allows them to power several different tools.
Bow Cutters
Bow cutters come in a few sizes. These small tools cut through foam very easy and allow the artist to shape the foam by removing the undesired foam. The most popular sizes are the 48″ bow and the 24″ bow.
Both bows are excellent and are the primary tools to use.
Two Man Cutters
A two-man cutter allows the length of the wire to extend well past 48″ and on to 6, 8, and even longer lengths. This tool allows you to cut billets of foam on their sides to create smaller manageable pieces. You can get creative with wire cuts and manipulate the wire easily. A professional note on the two-man cutter is when using the tool on longer cuts make sure you have patience. The wire in the middle of a 8′ billet is somewhat slower than that of the edges. The wire cools down while cutting and the slower you go the more accurate the cut. If you speed up the cut too much and go into turns or 90 degree cuts you could have a tremendous curve out in the middle of the billet your cutting. You will have to go back and trim out the middle for the extra foam. When following a design another trick is to plot out the path with numbers and only advance as far as your working advances. Make sure the plotted numbered path is oppositely drawn out. Meaning clockwise on one side is counter clockwise on the other side.
Sip Groover or Scoops
These tools come in many sizes and are basically large oven elements plugged into the wall. They get very hot and create a lot more smoke than their wire counter parts the bow cutters. These tools provide a different service than the bow cutters. These tools can “dig” into the foam and create spaces and voids in the foam where bows cannot. They are an excellent trenching tool for wire and pipe. Scoops can also come in handy for slight design work and final touches on a piece before hard coating. Drafting out water ways and water weirs is also a common project for this tool.
Unlike the bow cutter when the power is cut off the wire cools very quickly. In less than 5 seconds you can grab the wire and not get burned, however, scoops stay hot for a very long time and really burn you bad if you pick one up even minutes after the power is cut off. They can also damage property if carelessly placed down while working. If you leave the power on the element gets so hot that it will glow a bright red.If this happens you may start small fires while cutting foam. It will take cut or two too get the element back down the regular cutting temperatures. The smoke produced by cutting foam is absolutely not good to breath so stay in a well vented area and make sure you’re not breathing the fumes or wear a respirator.
Hot Knives
Knives are good for many things and are very useful for intricate cuts and higher detail work.
Knives are great but will not be efficient with the bigger cuts. There are also a variety of tools and extruded pieces that can be attached to knife bases. Knife work is a little slower but allows details to be achieved.
When Cutting Foam
I mentioned this before but I will say it again.
Do not breath the smoke caused by cutting foam. Well ventilation is best and wear a respirator. When cutting a fine line with the knife or scoops take in to affect the heat of the tool. You can follow a line good enough but if the tool is too hot it will over melt the foam and your line will disappear.
Foam Glue and Foam Fastening
There are many glues for foam available. They are applied to one side or both pieces needing to be put together. They are good products and I have used them many times. I also have used less expensive products like Great Stuff or any expandable foam product for putting pieces together. Just spray a heavy coat on one surface and wait about 1 minute on average until the foam has had a chance to gas up. Once the foam has gassed up smear the foam flat creating a very sticky epoxy-like substance that will harden fast and meld the two pieces together. When dry this bond is ridiculous and will not fail
.If you smash/smear the foam down to soon the foam will still rise and separate the two pieces slightly. The bond will not be as good but should still hold. You can also use 12′ landscaping spikes to hold foam pieces together until your read to glue. Even after your done gluing the foam together you can still use the 12″ spikes to carry the piece around. I have even structure coated right over the piece with the spikes still in the foam. You can remove the spikes anytime but they do make great handles for moving around.
Black Markers
Yah, they are like carpenter’s pencils. You can never have enough of them. But seriously, black markers work best to mark and design foam. They work really well until the foam gets wet. It’s very hard to design with wet foam.
Wet foam also is very hard to cut. The water is constantly cooling down the elements or the hotwire so keep the foam covered if outdoors.
Waste is a Big Issue
It always amazes me how much garbage or scrap can be produced from a single billet of foam. The stuff does not pack very well and the best way to deal with it is to cut it up is small pieces and bag it.
If you are on a bigger project (5 – 10+ billets) you may want to get a super sack. These extra-large industrial bags hold a lot of waste and many times the manufacture will take back the scrap on multiple delivers. This will save you waste and dumping fees as they will recycle the foam if its clean. That means no junk, glue, concrete, or other substances that will pollute the recycling process. I have heard of people burning the waste in 55-gallon drums, in fields behind very large industrial complexes to avoid the hassles but I don’t know anything about that.
Other Tools
There are a few tools that I have used over the years that are good to have as well. One is a propane torch or a small sweating torch. I use these to heat up rebar or pipe to burn a channel through foam for wires or water pipes coming up through features. Small saws or hacksaw blades also can be used for small adjustments if you don’t want to wait for the scoop to heat up. Chalk lines for marking longer lines, various levels, and 16 penny nails also work well for temporary marks or pinning down wires. Straight edges and measuring tapes are always being used.
Rasping tools are also good to prepare a surface or level out an area.
For the most part that covers the basics that you would need to be efficient.
Cement Coatings for Foam Core Construction
Structure coat from Walttools is the only product I use for its reliably and price point. Don’t make the mistake of just putting your vertical concrete mix over foam without this protective and structural coating. One half inch of this material creates a monolithic structure with 12,000 psi of strength and good floterial properties. The fiber enriched mix guards against cracking and load deflection. Structure coat also provides excellent scratch coat surface when sprayed by mortar sprayers. Once the entire surface is covered you are now ready for your vertical decorative concrete.
Now Your Ready
I have a special package of tools offered by Walttools.com that are professional grade and offer excellent durability and service.
Feel free to inquire
Nathan@VerticalArtisans.com
