Slippery Rock Gazette

Bob Murrell 

M3 Technologies

Photos by Bob Murrell

At the time I began this article, it was still February and mostly cold here in East Tennessee. A local restoration contractor asked me if it would be OK to color enhance a honed Pink Tennessee marble front porch, after stripping the old sealer off and honing to a 100 grit. The weather was to be in the mid-50s for the week, the sun was going to be out, and the porch was covered so I said, “Maybe.” Theoretically, the temperature is supposed to be above 50°F to apply most impregnators, color enhancers, and sealers, so (and hopefully by now, you know my standard response) I said, “Do a test to confirm both the results and procedure, prior to general application.” 

The porch was stripped using conventional high pH stripper and black pads. There were several coats of acrylic sealer, and who knows what else was applied through the years. The house was over 100 years old and the marble was quarried locally, back in the early 20th century. Most of the existing sealers came off except for the oldest, which was quite stubborn. It was decided that some honing would definitely be required. 

Above, left: Years of coating degradation and soiling are really noticeable on the low areas at the joints. Some of the Tennessee Pink marble beauty still shines through. Above, right: Initial condition of the porch, Before any cleaning or stripping.

It was necessary to apply stripper by hand in the low areas. Even in the warm sunlight, it was still cold enough to need a warm hoody, indicating the temps were still too cool for applying color enhancing impregnator. Notice the chiseled-edge capstone on the porch wall.

The edges had the most issues, as they weren’t worn off from foot traffic, so they were honed first using Flexible Metal bond diamonds ELF5-220 with a Makita right angle variable speed tool. The edges were especially bad, but once the edges were cut in, ELF3-220s were used under a 20” floor machine to do the field and overlap the edgework. The porch floor was fairly flat (with minimal lippage) but some lower areas had to be touched-up with the hand tool. 

After the edges and field of the floor had been honed to 220 grit finish, the process left a pattern from the electroplated flexible ELF series diamonds, which was to be expected. At this point, a 100 grit PLP diamond impregnated pad was used to make everything consistent. The porch had a nice matte finish and looked great. 

The weather forecast was monitored and after the third day of 50°F afternoons in a row, the color-enhancing impregnator test was performed. Unfortunately, it was a failure. The reason for this was actually pretty simple. The mid-afternoon days did reach the mid-50 degree mark, yes. However, the nights were in the upper 20s and low 30s. So, the marble never reached the 50° mark and was too cold for the process. The color enhancing impregnator congealed on the surface and never penetrated satisfactorily. This was a new bottle of a very good and expensive impregnator (Akemi Color Intensifier). I inspected and knew the product wasn’t the problem. The stone was just too cold for the process.

It was eventually decided that the color enhancing process would be rescheduled in April when warmer temps would be the norm. The contractor was paid for the stripping and honing processes that had been rendered and would come back to color enhance when the temps were above a 50°F daily average.

Of course the temperature also plays an important role in warmer seasons, as well. This is especially true for the southeast and west. Exterior projects can suffer from too much heat, most certainly when exposed to direct sunlight.

I have attempted to apply an impregnator in the direct sun during summer months, and (I’m ashamed to say more than once…) had miserable results. Planning for the different aspects of the project is paramount. Applying impregnator in the direct sun will evaporate the carrier (water or solvent) prematurely and prevent adequate penetration. This will ultimately result in excess product usage and therefore higher product cost, and could result in poor performance.

Using a color enhancing impregnator in the sun, and when too warm, could result in an inconsistent appearance. There may be more penetration in some areas than others. I definitely advise against making this mistake as this can sometimes be difficult to rectify.  

Above, left: Stripping with black pads and conventional high alkaline stripper before running a 100 grit PLP dip. Above, riight: The edges and field of the porch have been stripped and honed to 100 grit, but it’s still too cool to apply the enhancer. The contractor will come back in April when it’s warmer, to complete.

Now for the topical sealers. If the stone or masonry surface is too hot, the carrier may once again evaporate too quickly. This could result in the product not leveling satisfactorily. Brush, roller, or applicator patterns may be left in the coating. Sometimes, these application marks can be buffed out. But if they are too 3-dimensional, you may have to strip and start over. Diamond impregnated pads (DIPs) can occasionally do the trick by lightly honing the coating surface. In any case, subsequent applications should be done mid-morning and/or before direct sunlight will be a factor.

I call it the Goldie Locks temperature. Not too cold and not too hot – it’s just right. I would pick between 65° and 80° F as my Goldie Locks temp, with little to no direct sunlight. Of course, these are my preferences. Even though I have a few years in this business now, I suggest you check with the product Application Sheet, Data Sheet, and SDS for specific application instructions, technical tips, and safety guidelines. Always follow local, state, and federal waste guidelines.

As always, I recommend submitting a test area to confirm the results and the procedure, prior to starting a stone or hard surface restoration/ maintenance project. Also the best way to help ensure success is by partnering with a good distributor, like BB Industries, that knows the business. They can help with technical support, product purchase decisions, logistics, and other pertinent project information.

Bob Murrell has worked in the natural stone industry for over 40 years and is well known for his expertise in natural stone, tile and decorative concrete restoration and maintenance. He helped develop some of the main products and processes which revolutionized the industry, and is currently the Director of Operations for M3 Technologies.