Etching

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dbgpowerwash

New member
I did a restaraunt the other day and everything turned out great for the most part.... I was able to get all the gum up exept for the area around the beginning of the drivethru. It was weird, I could hardly even spray the concrete without having it start to etch it. I decided I would figure another way to get the rest of it off rather than tear up someones concrete. I dont think it was new concrete either so I dont know why it was so soft. Any ideas on how I could get the rest clean without damaging the concrete? I tried to scrape it but it was so old that just didnt do much at all. Any advice would be appreciated.
 
I just did a large gum removal project this past weekend using hot water and a 1,500 PSI nozzle. It turned out great with no etching!
 
I always use hot water. I turn it up as hot as it will go, I think I remember that I was able to get it up to about 230 degrees...
 
If you are using a ball valve turn the pressure down on the valve and the water will get hotter. It will also be less pressure on the concrete.
 
I pop gum at 125 •
What is the tip size. I also doubt your at 230.
Did you have a temp reading at the gun?
 
dbgpowerwash said:
I always use hot water. I turn it up as hot as it will go, I think I remember that I was able to get it up to about 230 degrees...
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What the dial thermostat knob says and what really comes out of the heater are two completely different things.

The only way you know the temperature of the water coming out of the heater is with a temperature gauge. Do you have a temperature gauge or just going by what the markings on the knob read?

You can pop gum at the 170 degree setting a lot of the time but the hotter the faster the gum comes up until your machine is spraying steam, then it slows down some (if your machine has a steam valve).
 
dbgpowerwash said:
I did a restaraunt the other day and everything turned out great for the most part.... I was able to get all the gum up exept for the area around the beginning of the drivethru. It was weird, I could hardly even spray the concrete without having it start to etch it. I decided I would figure another way to get the rest of it off rather than tear up someones concrete. I dont think it was new concrete either so I dont know why it was so soft. Any ideas on how I could get the rest clean without damaging the concrete? I tried to scrape it but it was so old that just didnt do much at all. Any advice would be appreciated.
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Are you sure its not seal coat? does it connect to a asphalt parking lot?
 
I think some of it might be seal coat, but some definetely is gum. My main problem is I cant even get close to the concrete at all or it starts to etch it. It is the black colored concrete that you see in a lot of drive thrus.
 
Now I'm scratching my head! :scratchhead: I don't think I've ever seen black Concrete. Is this something you ran your surface cleaner over as well?
 
I have seen large areas of concrete that they sealcoated to match the asphalt, I guess to hide the ugly concrete.

You have to be careful with sealcote, once you start removing it, the concrete will really stand out and they will want the sealcote replaced.

Have you looked at the surface in the daytime?

Got any pictures in the daytime?
 
Larry Millette said:
Now I'm scratching my head! :scratchhead: I don't think I've ever seen black Concrete. Is this something you ran your surface cleaner over as well?
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All the Sonic's and several other drive thru's out here in AZ have black concrete. Not sure if it's a colored concrete they add when finishing the concrete, or if it's a solid black. But I've thrown everything I own at some of that black concrete at several Sonic's and didn't faze it at all.
 
Jim Cooney said:
All the Sonic's and several other drive thru's out here in AZ have black concrete. Not sure if it's a colored concrete they add when finishing the concrete, or if it's a solid black. But I've thrown everything I own at some of that black concrete at several Sonic's and didn't faze it at all.
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Hmmm! Thanks Jim...I wasn't doubting it, I've just never seen black concrete nor have I heard of it...Black asphalt yes, but not concrete.
 
The color is added when they mix the concrete.We clean a few and have no problem with the creme coming off.
Most customers who have colored concrete think it won't be noticabley different after cleaning.I always love the look on their face when they realize it's 6 shades lighter because all the oil and other junk is gone.
 
When I was learning how to do parking lot striping back in 2005 in North and North-East Texas and Texarkana, a lot of contractors would use the H&C Black stain to color their concrete to keep it looking good for a long time. It also hides the oil stains for a long time also. The colored stripes really look nice on the black background.
 
There could be a lot of reasons for this, and few of them are your fault.
Since you are in Phoenix, many of the concrete contractors feature employees that are not from around these parts, and really do not have a comprehension of the concrete trade. That being the case, they add extra water to the load of concrete to make it easier for them to work. The problem is, when you add water to the mix, it reduces the strength rapidly, so that it cannot handle the pressures that we use for cleaning.
This also could be a case of a strip of concrete being hand mixed, which is less exact than a concrete company provides, with the same result.
Either way, very low pressures, very high temperatures, and time will make it so that you can remove the gum.
 
David O'Connell Jr said:
Wow talk about PC :yikes:
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:killingme:

But Scott has a great point. I have experienced certain situations where one section of a slab will stripe, and the rest of the slab turns out perfect.

I've been in the construction business most of my career, and have witnessed mixers lined up 3 to 5 at a time. The mix starts getting "hot", and they add water to the mix to keep it workable. This explains the deterioration of the density of the concrete once cured, especially the cream.

I bid a job today and where the roof drain spilled out onto the concrete it was maybe 1/8" etched and the aggregate was exposed big time.

Craftsmanship in the past 10 years took a turn for the worse in the construction industry, at least in this part of the Country. Cheap labor was favored by the greedy contractors, and the "foremen" and "supervisors" qualified by being bi lingual, instead of journeyman and length of tenure.

That's as "PC" as I can muster.
 
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