Is the Festool RG130 Diamond Grinder suitable?

[Red Bicycle]

Dear All

I wish to remove all the paint from rendered brick walls in my unit. There is a mixture of many layers in this 50 year old unit - old (probably lead based) paint, 20 year old Porters Lime wash and new acrylic on the walls. it is the Porters that has caused the problems as covering with Porters Lime Blocker did not work at all and the acrylic paint overcoat is prone to peeling.

I'm looking at the Festool RG130 Diamond Grinder which I can also use in my business for tougher jobs but want to know if it is up to the task of removing paint without damaging the rendered surface by gouging or like. Has it got the finesse to just remove the layers of paint?

Many thanks if you can provide some insight.

Best

Michael

 

[leakyroof]

Can you post of picture of the work you need to attack with whatever tool you end up with. Several professional painters post here regularly, and can comment to how they'd do it.

 

[Sparktrician]

Don't do it!!!  The RG 130 is meant for resurfacing concrete and the like, and will eat brick like it's peanut butter.  Some of the painters here on the FOG may have insights as to how to strip the paint from brick non-destructively, but the RG 130 is not the right tool. 

 

[Kev]

Can't you use a stripper?

Do you care about the brick surface or do you just want a stable base?

Kev.

 

[AlexThePalex]

I think the only proper way to do is to sandblast it. A brick wall is highly irregular with lots of nooks and crannies. I agree with Sparktrican that the RG130 grinder may be way too agressive. And you won't get the desired result anyway because you can't reach into the mortar joints.

If you really want your wall to look like a stone wall again you have to sandblast it. An acquaintance of mine has a company that renews mortar joints, first they remove the old mortar with air chissels and then they sandblast the entire wall, it removes the ugly discoloured top layer and the stone looks like new again.   

 

[Red Bicycle]

Dear All

thanks for the replies but I may not have been clear in my original post. The walls are rendered with a sand and cement mix which  produces an overall smooth finish yet it is quite textured. I have tried stripper but it can not be removed easily and creates more work than its worth. There is a product here in Australia that will take layers and layers of paint off by placing specially coated paper over the paint but it would cost more than the Grinder to use. The bricks are not exposed but I don't want to damage the rendered finish too much even though I will be applying a matte acrylic finish over it.

Thanks

 

[Thunderchyld]

Rendering sounds very similar to the finish coat for cement pools, a surface I've had to clean a few times.  My suggestion would be blasting, either soda or sand.  Soda blasting would probably do less damage to the render, but even plain sand or straight abrasive will probably do less damage than a grinder. 

I haven't had a chance to use it myself yet, but have heard good things about dustless blasting.  Dustless uses recycled glass as the abrasive and both air and water as carrier.  The wet action is supposed to be very effective in keeping the dust down. 

 

[greg mann]

I have heard of systems using dry ice is a blast media. That might work as well.

 

[Sparktrician]

I'm with Alex and Greg that blasting, either sand, soda or dry ice, is likely the least destructive manner of removing the render's coating while preserving the brick substrate. 

 

[Thunderchyld]

I've worked with a dry ice blasting system before.  They're freaking awesome!  Amazingly clean, all that's blasted off is the grime, the dry ice sublimates on impact.  That sublimation is the key to dry ice blasting.  The dry ice sublimates on impact, expanding into a much larger volume of gas.  I don't recall the exact figure, but the gas volume is quite a bit greater than the solid volume.  The idea is that the dry ice particle gets forced behind the paint, grime, etc and then sublimates and the gas then "blows" the grime off from it's weakest side. 

Now, on to the negatives.  OMG, are they expensive!  I could probably call Festool and say I'll take one of everything available in the US and still not spend as much as that dry ice system would have cost.  I don't recall the exact figure, but the contractor who brought in the system I got to use said that his full system cost him more than his new F450, and that wasn't counting having to have a liquid CO2 bunker at his shop to feed the pelletizer.  Oki, just googled prices.  Can't find new, but used are around.  Blaster runs anywhere from 7k on up, pelletizer or block maker another 10-20k.  So call it at least $20k to get started used.

Speaking of negatives, theres one of them right there, pelletizing.  You either need a manufacturer of dry ice local to you or you HAVE to buy the gear to make your own pellets.  Part of the reasoning behind this is that the machines have trouble with older pellets, they get stuck, don't grind to dust as easy, etc.  So not only do you have the gear, you've got a machine needed to produce dry ice pellets so you can have fresh top quality blast media. 

All that said, I'd still buy one IF I could be reasonably certain it would be profitable for the business.  There doesn't seem to be a better in-place method for the job I was involved in.  A few years back, the statewide smoking ban came upon us, and a few businesses were doing deep cleans, to try and get rid of the lingering effects of the smoke.  The dry ice blaster seemed to be lifting the film right off of the wallboards without damaging the wood.  Where the blaster really shines, pun intended, is in cleaning in the kitchen.  Seen some pretty bad range hoods in bars, the one in that establishment was so dirty, and had been so dirty, that when we cleaned it the bar owner was shocked that it really was stainless steel.  The dry ice blaster seemed like a miracle with that hood.  Point the wand at it and the grease would just blow away.  Probably the nicest thing about using the DI blaster on the hood was that the grime coming off of it tended to stay together and fall to the floor.  Normally, when using a pressure washer on a range hood, you start in one corner and endeavor to "push" the sludge away from you.  Of course, what happens is that you get a kind of "wave" of sludge rolling across the steel, splatters, and its' dripping and splashing all over the place.