Edge finishing is an age-old gripe with polishing contractors that has caused bad backs and sore knees since the beginning of polished concrete time. I wish I could write an article that would take away all your frustrations about edging, but I can't. What I can do is offer an article that presents solutions for the difficulties contractors often stumble upon during the edging steps of a polished concrete floor.
Successful edges start with attitude. A hate for edging can spread like a cancer through your company, so you must ensure a positive attitude about edging at the top of your company. Your employees need to know edges are an essential part of the overall beauty and finish of the floor and are the key to your company's profits. Employees who take their time and use their skills to produce beautifully blended edges should be commended and rewarded at the end of a project. An attitude adjustment like this coming from the top of your company will help ensure your projects are an overwhelming success.
Other challenges that can affect the outcome of edge work can't be solved by a simple attitude adjustment. Oftentimes, inconsistent concrete finishing along exterior walls is the result of concrete contractors having to hand-finish edges because their power trowels couldn't get close enough to the edge of the slab. Hand finishing can cause many frustrating situations such as an uneven finish with many highs and lows and "chalky" concrete or pitting. These problems can all be solved but only with elbow grease and backaches. I like to try to get the edges as flat as I can and blemish-free by heavy grinding or patching if necessary.
Another issue is timing and the construction schedule. Was I scheduled before drywall and baseboards? Are the toilets in? What about kitchen cabinets? The project manager always asks me when I want to come in to "do my thing." Of course I want to be free and clear of obstacles and interior walls, but a large percentage of my jobs start before the concrete is poured. I cannot expect the GC to wait 28 days until the concrete is cured before he can start rough framing or other tasks on his own schedule. I try to explain what works best for me and is most cost effective for him in regards to edging and we make an educated decision.
Choose the right tools
There are enough factors working against you when you're polishing edges on a concrete floor. Do yourself a favor and don't work against yourself even more by using the wrong equipment and subpar diamond abrasive pads.
Handheld, on-your-knees equipment
- 7- to 9-inch high-speed grinders with a shroud and metal cup wheel abrasive are generally used for the first cut or coating removals.
- 7-inch variable-speed grinders are often seen in a non-shrouded application with resin diamond pads and generally used in conjunction with the grinding steps of the floor machine.
Stand up and get off your knees equipment
- A handheld 7- to 9-inch high-speed grinder attached to a carriage, again typically equipped with a shroud and metal cup wheel abrasive and used for the first cut or coatings removal.
- A 2- to 3-hp stand up edger with single rotary head and articulating body for forward edge grinding.
- Counter rotary head stand up grinder.
Know the edging process
The challenge with edging is this: How do I use a smaller edging tool to match the polish made by a much heavier machine? Let me share with you my process for this procedure.
Usually you have at least two people on the job — one edging and one running the machine on the rest of the floor, moving both projects through the same grit sequence at the same time. In rare situations I have done both, grinding a few passes then playing catch-up with the edges or vice versa. Ideally you want to be chugging along at roughly the same pace.