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Posted: Mon Oct 08, 2007 10:47 am
by fallguy
Hello guys , i'm not sure if this is the correct forum for this
question but anyway's i'm sure someone in here can offer some
advice .Some fool has painted part of the house wall with
red paint around the back of the house (looks like it was to cover up some
white paint marks).It looks AWFULL 
.
I had a go at getting it off with paint stripper and after about 3 applications it got the top off and faded it a bit but the paint has soaked into the brick pores .Is there a special paint stripper I could try ?. A friend told me to try sandblasting but I got no previous experience of this ,would this restore my housewall. ?
Any help an advice with this would be appreciated .
Thnx in advance .
Posted: Mon Oct 08, 2007 3:58 pm
by RAPressureWashing
fallguy wrote:Hello guys , i'm not sure if this is the correct forum for this
question but anyway's i'm sure someone in here can offer some
advice .Some fool has painted part of the house wall with
red paint around the back of the house (looks like it was to cover up some
white paint marks).It looks AWFULL .
I had a go at getting it off with paint stripper and after about 3 applications it got the top off and faded it a bit but the paint has soaked into the brick pores .Is there a special paint stripper I could try ?. A friend told me to try sandblasting but I got no previous experience of this ,would this restore my housewall. ?
Any help an advice with this would be appreciated .
Thnx in advance .
Hello Fallguy,
Yes sand-blasting would work on this,
There are other strippers that will work, but I would need to know a couple of things first.
What type of paint is it?
What condition are the bricks in?
can you post a photo of the area to be cleaned?
Posted: Tue Oct 09, 2007 11:00 am
by fallguy
Hi Roger
Though I can't be 100% sure on this, the white paint
marks underneath look like oil based white gloss .
The red paint must be that red gloss brick and tile paint sold in diy
shops (found an old can in the shed on the can it says petrolium solvent
base (naphtha) .
The bricks are in good condition ,sorry don't have a digi camera to post
pics but the area to be cleaned is about 10 sq M .
Regards kev
Posted: Tue Oct 09, 2007 11:58 am
by RAPressureWashing
Kev,
There are 3 approaches to this,
1, Hot water pressure washer, 120+degrees should work.
or
2, A caustic will also get this off, I make my own strenght mixes for stripping old decking stains etc. I could send you info on how to mix this, but be warned it is nasty stuff to work with.
or
3, Have a look at this site, http://www.tensid.com/index.php
What you need would be AGS Graffi Clean 400 it's also bio-degradeable.
I think 1 & 3 are your safest options.
Are you near the London area?, as I could try to have a look at the said paint.
Posted: Sat Oct 13, 2007 11:45 am
by fallguy
Hi roger
Thanx for your tip's .I decided to try the cheapest
of the solutions you suggested 
,the caustic stripper.
I thought this might involve sodium hydroxide (which I have
a readily available source of ) so I did a quick search on the
net for caustic paint stripper mixture ,and found this posted
on some forum.
"300g caustic soda per liter of water then mix with any flour to form paste .Paste on wall and leave for 48 hours ,then wash off
with water ".
Before I try it , could you just confirm or correct it for me.
Best regards Kevin (p.s I am nowhere near London i'm in Stoke)
Posted: Sat Oct 13, 2007 1:22 pm
by RAPressureWashing
Hello Kevin
Yes sodium hydroxide is correct, When I am stripping oil stains sealers etc from wood, this is the mix I use 16oz of sodium hydroxide to 5 gallons of water plus a couple of squirts of a liquid soap, I use sainsburys baby shampoo as it has noting in it that will react or fight the sodium hydroxide.Dwell time is 30 mins, don't let the mix dry out on the surface. You may need a couple of applications to get rid of the staining. I have had to step up the sodium hydroxide to about 3ibs in 5 gallons of water for really tough stains. Now you are working on a wall as opposed to a horizontal surface, so it's going to run down, watch where your run-off is going as the caustic mix will kill grass plants etc.
PPE, you are going to need goggles, nitrile gloves, and I use a resperator mask. The mix will get hot and will burn your skin on contact if you do not take care. Remember add the sodium hydroxide to the water NOT the other way round. I have not used the flour method, but it does make sense seeing as you are working on an upright surface.
Posted: Wed Oct 17, 2007 7:40 am
by fallguy
Hi .
The good news is that the pure sodium hydroxide solution works well but
it's hard to apply .(all my paint brush brissels dissolved as well).
I tried to mix a poultice out of it so it would be easier to apply and remove .I tried mixing with flour as was said above ,but baking flour reacts with the solution when you add it (turns the flour into hard lumps of plastic).
I just think i need something more inert to mix with the solution to make a poultice/paste.
Posted: Thu Oct 18, 2007 5:49 pm
by RAPressureWashing
Kevin,
Don't know what to suggest re the poltice, as it is not a method I use. If it is any use I spray the caustic mix on, I have 12 volt pumps for this, you can use a pump-up style sprayer, but again be careful, as the caustic soda can and most prob. will melt the seals etc, also with caustic being an unstable chemical caution is needed when it is under pressure.
You might be better with a nylon bristled brush, if you have to go the brush on route as it should hold up a bit longer.
Posted: Fri Oct 19, 2007 11:48 am
by TarmacLady
Try going the other way round -- mix the flour and water, but leave it as a very loose slurry -- then add the sodium hydroxide -- but try it small-scale first, so you don't have to throw a caustic mess in the tip if it goes off.
Posted: Sat Oct 20, 2007 9:12 am
by matt h
USE PLAIN FLOUR, AND CLEAN WATER. then add causticTEST SMALLAREAS FIRST WITH DIFFERENT STRENGTH OF MIX. ALLOW 10 MINUTES AFTER APPLICATION AND TEST REMOVAL BY EXPOSING UNDERSIDE OF POULTICE WITH PALLET KNIFE. IF IT HASNT REMOVED THE FULL PAINT LAYER, RECLOSE THE POULTICE AND RETESTafter further ten. This method works on plaster, metals , wood and brickwork, but you must wash down with copious amount of water after , except with plaster covings where the mix should only be weak, and removed as soon as the paint layer is breached..it can be carefully peeled off by use of pallet knife. :p
Posted: Tue Dec 11, 2007 5:35 am
by BC4ME
Blasting with baking soda, walnut shell, or corn cob media would be best. Sand or other hard abrasive will strip the 'skin' off the bricks, allowing water to get in and gradually degrade the brick.