another brick question

[troyt 14]

I have a brick building to clean, it has efflorescence comming from the sprinkeler system, under the efflorescence is rust, comming from the same system. Should I treat them as one stain, or each individually. What I mean is should I use diluted muriatic acid then follow with oxalic for the rust, or will one take care of both?

[troyt 14]

Ok, I tried the oxalic acid first, I like that acid, anyway it seemed to disolve the efflorescence, but when I returned, it more or less just spread it out more evenly. Maybe I didn't rinse well enough I used a pump up sprayer to apply, then used a different pump up srayer with warm water to rinse, please see the photo. Anyway, I returned and applied muriatic acid, and followed with a heavy rinse from the p/washer, will upload the photos from that one after I take them, which with the rainy weather could take a little while for the brick to dry. Any ideas or hints would be helpful and I would be most thankfull.

[troyt 14]

I went back to take a photo, but after the muriatic acid, and lots of rinsing, there is no change. The only thing I can think of is that the salts are in the brick and just keep comming out. This building has never been washer, except for rain, and years of salt could just be comming out. How can I fix this.

[chirobob 14]

Try brushing on HF starting at 1-2% with a truck brush on an extendable pole. Make sure you wear a full facemask and PPE gear. If this doesn't work try increasing the concentration factor up to 5 % and then 10% but be very , very careful. When you rinse it off, I would first give it a low pressure volume rinse followed by a high pressure rinse.

Jason

[troyt 14]

Thanks Jason,

I read on the BIA's site to mix ammonium biflouride with the oxalic to make HF, yet HF still worries me, and I can't secure it in small amounts. Does anyone know if ammonium biflouride is readily available? I think my problem may also be I am not saturating the surface well enough before applying the acids, thus I am bringing more to the surface when the rinse water is evaporating.

[chirobob 14]

Thanks Jason,

I read on the BIA's site to mix ammonium biflouride with the oxalic to make HF, yet HF still worries me, and I can't secure it in small amounts. Does anyone know if ammonium biflouride is readily available? I think my problem may also be I am not saturating the surface well enough before applying the acids, thus I am bringing more to the surface when the rinse water is evaporating.

Troy,

this is a pic of me applying HF @ 2% and the safety criteria, I religously follow when dealing with HF. 2 x Chemical suit inner + outer, full face respirator, hard hat , ear muffs to keep hard hat in place, steel capped chemical rubber boots, disposable ntrile gloves under PVC chemical gloves.If I am dealing with any chemical I wear this at all times when applying, only when rinsing will I take the mask off.

I would also be wary of mixing two chems together to make the HF as you need to know """"""""EXACTLY""""""" what is going on with the reaction to determine to """""EXACT""""""" percentage of HF.

Cheers

[paul-uk 500]

troy when treating efforessence never use full power face on always do it from the sideto try and wash it sideways as you will only drive it back into the brick....witout the proper chems for the job looking at your pic i think you have a big job on....there are a couple of websites i would contact and send the picture to them and follow their recomendation.....prossoco...dietricht...domres.com.....have a look at these sites and read up on it.......paul.

[troyt 14]

Thanks Paul,

I tracked down the mfg of the brick, and they recomended a chemical from Prosoco called Sure Klean, I am going to try it in a little bit. Thanks for the tip about not hitting the brick head on. I know I should never do that, but sometimes I forget, lol. I get caught up in the moment from time to time.

[troyt 14]

How deadly is HF on plants, as you can see from the photo, it will be next to impossible to reclaim the water from these stains. The building has a grassy hill leading up to the brick. Is HF worse than other acids, once it is diluted and in the ground?

[RyanH 14]

Try to keep the final concentration on the ground to a level below 2 ppm (.0002%). Basically, flood the area that will come in contact with the acid, spray the wall with your solution, flood the surrounding area again while the solution dwells, do your washing thing with the wall, then rinse the area again.

You're going to have a problem with that window, though. HF is used to etch glass, so getting any overspray or drips on it will ruin the surface, even with frequent rinsing. I would cover the entire window with plastic and tape it off such that you have a good overlap of seams and that any water running onto the plastic will not make contact with the glass (overlap the seams top sheet over bottom sheet, not side by side).

And use that safety gear....the previous poster is absolutely correct about religiously using gear on something like this. HF is nasty stuff and you don't want that monkey on your back.

[troyt 14]

RyanH,

Thanks for the good advise, Prosoco is sending me some chemical samples to try, I looked up in the MSD's for them and one contains HF, so time to buy some heavy duty safty gear and learn how to work with this stuff. Here is a question, I can buy HF from a local trailer mfg, in 5 gal pails. Now, what would be the best way to pour this stuff from a 5 gal container into one that is smaller and more easily worked with. I am a good poured, but a full 5 gal container, that is a different matter. Lots harder to control.

[paul-uk 500]

try the proper chems for the job before you start messing with hf....if are not sure how to handle hf appropriatly you would be more than foolish to want use it on a job....

[troyt 14]

Paul-uk,

I completely agree, I have not yet received the product with HF in it (Prosoco's 1261 Hard Water Deposit remover), I did think of trying a different chemical, Wal-Mart sells a product called Kaboom, and that does seem to be having an effect. It seems the stains are white scum or Hard Water deposits, and something in Kaboom is working. I looked up the MSD for Kaboom, and the only active ingreediant listed is Urea Monohydrochoride. I don't know if that is the chemical responsible for removing the white scum, but something like Kaboom but a little stronger, I feel will remove it, and keep me from having to learn how to use HF, which I really do not want to even have in my chemical collection.

[RyanH 14]

HF manufacturers suggest storing the acid in a particular type of plastic bottle due to its proclivity to degrade glass and corrode metals. You might can use one of the plastic hand pumps used for the 5 gallon kerosene fuel cans that you usually get with an indoor kerosene heater. I know they sell for around $3 at home depot and Lowes. I don't think they would be a seasonal item. If not there, support a local small hardware store and check them out....they usually have EVERYTHING you need and can't find elsewhere.

Before jumping on the HF bandwagon, though, I'd take the advice of paul and troy...if you can find something else designed for the white stuff, give it a shot first. There is no point in endangering yourself unnecessarily. If you do decide to use HF or HF containing products, pay particular attention to the TLV and TWA numbers given in the MSDS.

[troyt 14]

Ok, Newbe here, I know what MSD's are but TLV and TWA, what are they?

[RyanH 14]

TLV-C = Threshold Limit Value Ceiling...basically tells you the maximum concentration to which you want to expose yourself, or don't want to expose yourself, regardless of how brief the encounter.

TLV-TWA = Threshold Limit Value- Time Weighted Average...the "average" maximum exposure to which you are exposed to over an 8 hour period...HF is around 3 ppm I think.

TLV-STEL = Threshold Limit Value - Short Term Exposure Limit....The maximum amount of exposure you can have in a 15 minute interval before suffering irreversible damage or excessive irritation...basically if you hit this number you may not be able to walk away from the situation....HF is around 6 ppm for 15 minutes.

These values are OSHA values....some other regulatory agencies like NIOSH are a little more lenient.

[Gavin 14]

Ryan, you're awesome! Where do you get this stuff? I'm just amazed at some of the info you guys go carrying around in your heads. Amazing! Thanks!

[RyanH 14]

Nah. I learned that stuff in a chemical safety course in the engineering program I went through. They wanted chemical engineers to be able to know and take into account with the design of a process the dangers of chemicals in question to be used. No point in trying to use a chemical as a solvent if it kills the people who come in contact with it for longer than 15 minutes or it explodes when exposed to air...that kind of stuff. We had to do so many case studies and evaluations on how to make sure rooms had adequate ventilation and concentrations would be in sufficiently low amounts so as not to cause injury that the stuff just kind of stuck. It's more useful to me now than it was then. Glad I could be of some help.

[CCPC 26]

After reading this thread, I think if I come in contact with somthing that can only be cleaned with HF then I guess its not going to get cleaned, by me at least.

[troyt 14]

I just received the Prosoco chemical samples. One is just strong HCL, the other HF. The packaging to the HF is enough to scare the crap out of me. The HF came in two cardboard boxes, inside of those a metal sealed container, inside of that container "which is cardboard padded" a plastic bag, with chemical absorbent cloth wraping the chemical bottle. WOW, I think I will just keep it all sealed and move on to the next project. BTW, anyone have problems with rust reforming on brick or cement after oxalic acid has been used. It seems to eat the rust, but after a couple of days is righ back, just looks smeared. I am not having much luck with this project, could be they keep watering with the dirty water, and I am back to square one again. Thanks for the information Ryan, it will come in handy in the future.