Here Is What I Am Upto This Week

BulldogMedia

Have a eye care center contact me about blasting three arched beams in a old building that they are moving to. Anyway when they had the old offices riped out they found around 2500 to 3000 sq.ft. of brick that they want blasted also. it has added another 4 or 5 days too the 2 to 3 day that I already bid.

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Tscarborough

Looks great. Please don't do that to an exterior brick surface, though.

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plazaman

How come?


Bulldog, looks great, crushed glass im assuming? How many layers and what psi?

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BulldogMedia

Yes crushed glass 40/70 grit at 70psi.

I would like to know why too. The company I bought my pot from has done historical buildings that the had to test blast first and then some architects and engineers look at bricks with microscopes and the said there was no damage being done.

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Tscarborough

Because the vitreous surface of the brick has been removed and it is about as pervious as a Mexican adobe.

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Tscarborough

Do you know how to do a water absorption test? Do one before and after, and note the results.

http://spam.concordia.ca/~raojw/crd/...say000285.html

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BulldogMedia

So the if that is the case why would a engineer let them continue with blasting and say there is no damage?

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Tscarborough

For the same reason an engineer would spec 1800 PSI mortar when 800 would perform better, last longer, and be more waterproof.

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plazaman

what about some type of masonry/brick sealer, maybe something like a silicone based product?

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plazaman

what distance? Nozzle size?

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Tscarborough

Yes, it should certainly be sealed (exterior).

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MEDIA MAN

Bulldog,

How many sq ft /hr do you think you are averaging? How many #'s media/hr are U going through?

MEDIA MAN

tscarborough,

Queston for you. Are there any immediate signs to look for on brick that has lost ifs vitreous surface? Are there any long term signs?

Tscarborough

Tap it with a hammer. It will either go "click" or "clunk". It is also pretty apparent visually, it will be coarser and bumpier than normal brick. If you sandblast and remove 1/16th or less (on newer brick, at least), there should be no problems, though it should still be sealed.

Long term, there will be water penetration, spalling and efflorescence.

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BulldogMedia

tscarborough,

I checked with who had told me this and I have to say I was some what wrong, sorry. We are not using sand and blasting the hell of it like some old sandblasters did. Anyway if I would do it on a exterior brick and seal it would that eliminate any problems?

plazaman,

We are at about a foot with a #5 nozzle

media man,

90 sq. ft. per hour
100# of media per hour.

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plazaman

media man, with your new nozzle, how much do you think production could increase?

Tscarborough - can you recommend a sealer? Maybe something from the SW line?

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Tscarborough

Well, there is no one sealer that works best for everything, but for general clean clay brick sealing, new or old, I have had very good luck with Prime-A-Pel 200. The ProSoCo line of cleaners and sealers offers a nice degree of specificity for the broad range of masonry products.

Also, let me say that I know very little to nothing about sand blasting, even though I do sell a large amount of silica and coal slag, along with a miniscule amount of glass bead. We sort of backed into the business, selling blast sand for finish coat stucco. If we were not already so busy we can't keep up, I would go full line with aluminum oxide, walnut shells and whatever else you crazy @#@%^ use.

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MEDIA MAN

Bulldog,
Thanks for the info on your current job. Sounds as though you are about right on track. Paint coming off fairly good. The results are looking pretty good too! Are you having trouble seeing, blasting in the basement. Is it your customers intention on leaving the brick bare?

Tscarborough,
Thanks for the usefull advice on brick.

plazaman,
my production seems to have doubled. I does not appear that I use any more media but it is consistant with the production. Meaning I am going through a pot faster than with my standard #5 venturie but not using any more, I get farther in sq. ft. per pot. The design of the nozzle is not to increase the blast pattern but in effect it does. Here's why: I see an increase in blast pattern size because i am farther away - therefore widening the blast pattern. The #5 venturie I averaged about a 3"-4" blast pattern @ 18-24" away. With the super stick I am now getting about 6" blast pattern @ about 36" away. I was told by my distributor that they say with this nozzle you should be able to blast up to 13' away. Meaning if you were blasting a room and the ceiling was 12'-13' high you should be able to blast it without ladders or scaffolding. I guess I'll see!

MEDIA MAN

Thanks for the info. This is good to know. Please educate me a little more. Blasting of brick is very common and can be a large portion of ones income. Should a person be weary of the vitreous surface on all brick? Is there any stone to be aware of? You mention blasting stucco - any precautions with it as well? Is there anyting special done to the surface of the brick during manufacturing of the product that creates this surface. If not why does removing the outer surface pose this problem. I would think that it should be the same through the brick?

On another note may I ask what you charge per pound of slag? (20-40 grit & 40-60 grit)

Tscarborough

Any brick that is more than about 60 years old is most likely not going to be fully fired. Newer brick is fired much more thouroughly, and thus has a thicker vitreous "skin". An easy rule of thumb is that if the color of the brick changes when you blast it, you are removing too much.

I am called to consult on brick repairs a couple of times a year on brick that has been blasted and is, basically, ruined. That is why I am a fanatic about never painting brick.

We do have special conditions in this part of the country, however. There is no freeze-thaw to speak of, and handmade wood fired brick are very common, as are used brick from Chicago. The Austin common and a couple of other 60-120 year old local brick are also very poorly fired, so there is a pretty good chance that anyone doing sandblasting here is going to be blasting thin skinned, soft brick.


We get .088 cents a pound for coal slag, .0445 for silica, bagged.

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