How do I remove tar from cement block?

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Old 08-06-11, 12:16 PM
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Question How do I remove tar from cement block?

The previous home owner painted the inside of the basement walls with tar to seal the water out. I don't know how that worked out for them but it's not working out any more. I would like to seal the walls with Thoroseal, but I can't seem to get the tar off. I have tried scraping it, I've tried muriatic acid and a wire brush. I even tried bug and tar remover, I just can't get the stuff off.
Water is seeping through it so it has to come off for the Thoroseal to be able to penetrate the block.
Any suggestions?
 
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Old 08-06-11, 03:47 PM
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I know it's a lot of work, but you'd be best off fixing the water issue from the outside. Then you could just paint over the tar with a latex paint to help dress it up.

Most any solvent will dissolve the tar but it will be messy. Make sure you have plenty of ventilation!!! I doubt muratic acid would have any effect.
 
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Old 08-07-11, 07:15 AM
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Not only would it be a lot of work it would be a major expense. This is an 11 block basement. Digging down that far would be a nightmare. The yard is landscaped so that it would be impossible to get any heavy equipment in the backyard where that water is the worst. It would have to be dug by hand out there.

There was an ad on the top of this page (before I logged in) that suggested something called Citrus King. Would one of those Citrus cleaners be strong enough to get it off. I'm willing to expend some elbow grease. The muriatic acid did make so you could scrape it off, but you had to move really fast before it hardened back up again. That got to be a losing battle after a few hours of it.
 
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Old 08-07-11, 08:03 AM
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As many will tell you over in the basement forum, coatings are not going to stop water infiltration. It is best to stop it on the outside. We already know digging up the outside and waterproofing is not something your wallet will allow. Have you done all the basics with the downspouts and fixing any possible grading issues? If that didn't solve your problem, then you can put up a barrier on the inside to direct all water flow into a weeping tile in the floor and then to a sump pit. Are you intending on finishing the space?
 
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Old 08-07-11, 08:25 AM
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The concept that coating will not keep water out is incorrect. I put Thoroseal on my basement walls in my old house and it completely stopped the seeping water. I know what you are going to say, must not have been much of a water issue. That would be incorrect too. I did as suggested, except I drilled weep hole in the base of the block and tried directing the water over to the sump pump. I found places where water shot out of the wall about 10 feet onto the floor. I plugged them with hydraulic cement and went and bought 15 pails of Thoroseal. After a second coat I had no more water problems. The guy who bought the house has yet to have a problem either. There is also another product out there created to do the same thing only it penetrates the block (or floor) to the point where it actually keeps radon from seeping in too. I don't have a radon problem so I stuck with a product I know.
I need to get the tar off so the Thoroseal can penetrate the block, it does not go over the tar very well.
 
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Old 08-07-11, 09:13 AM
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I'm skeptical as well (being honest), but understand your experience and options. There certainly are solvents that will dissolve the tar, but not sure you can live with the fumes they would leave behind. As a less toxic approach, and I have never tried this, would steam and perhaps a detergent offer any progress. Steam starts at 212, but can go much higher under pressure and I believe some rental places might carry them. Do be careful with whatever you try as safety is always number one.

Good luck, and be sure to let us know how it turns out.

Bud
 
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Old 08-07-11, 11:48 AM
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Never thought of steam but can give it try. I know gasoline will, but you are right the smell would be enough to really knock you on your backside. Wonder what a torch would do. I can just imagine the smell from that too
I have built steam boxes for bending lumber, I could try that approach. Will let you know.
I went up to the hardware store and got some of that orange cleaner for cleaning oil off the driveway, didn't even touch it.
 
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Old 08-07-11, 01:01 PM
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I think you will need steam under pressure.
 
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Old 08-08-11, 06:57 AM
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Oh.
The only thing I can think of that you could rent is a wallpaper steamer. Wreck that and I'd be buying it.
At this point I'm thinking I might try to go over the tar with the Thoroseal. If the Tar is that tight to the wall it should be sealed in those areas. The open areas will suck in the Thoroseal. Sounds nice in theory doesn't it
 
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Old 08-08-11, 07:27 AM
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I've never used any thoroseal and don't know much about it but latex paint generally adheres well to dry tar although on exposed exterior applications the tar can become soft and move around causing cracks in the paint. I would think the thoroseal should preform fine over the raw masonry, the biggest concern would be whether or not it adheres to the tar.

I doubt drooplug and Bud were talking about a wallpaper steamer but rather something on the order of a steam ginny.
 
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Old 08-08-11, 01:43 PM
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Hi Mark
Not sure what a steam ginny is???
 
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Old 08-08-11, 03:59 PM
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Think of a pressure washer [but not quite that much pressure] that shoots out steamy hot water. They are used a lot to clean greasy items - like an oily motor. Most have an oil burner to heat the water.
 
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Old 08-08-11, 05:05 PM
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Thanks Mark at least I came away frpm this experience with some kind of knowledge.
 
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Old 09-03-11, 01:56 AM
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Cool tar removal

Use WD-40 then Purple Power degreaser from Lowes or walmart in automotive. Then mild soapy hot hot water ( use a medium stiff bristle brush! THE WD-40 BREAKS THE TAR DOWN INTO OIL THE DEGREASER BREAKS IT DOWN EVEN MORE THE HOT HOT HOT SOAPY WATER SHOULD CLEAN EVERYTHING I'VE JUST TOLD YOU UP!
 

Last edited by kylehandy1; 09-03-11 at 02:04 AM. Reason: left some info out
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Old 09-03-11, 04:26 PM
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Hi kyle
I already put Thoroseal over it. I think I have another wall that might have tar on the bottom 2 course of block. I'll give your idea a shot. If I can break it down I can borrow the power washer from work and flush it off with the soap. They have one that is made to work with HOT water. Mine is a cold water use only.
 
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