Concrete curing question

[Epiphile]

Hi all- I've been working on a piece for a new viv I'm building, and just wondered if anyone else has come across a similar issue: after having cured for three weeks, my piece has developed what looks almost like a mineral deposit-like film over it which isn't visible when wet but really stands out when dry. I understand that it can be caused by various things (minerals in the water, salts in the cement, etc.), but I'm wondering how to get rid of it- even a wire brush isn't doing any good. I found that spraying with white vinegar made the problem worse, but perhaps it needs to get worse before it gets better. If anyone needs photos to help identify the problem I can post some. Oh, and I also made liberal use of an acrylic additive in my grout mix- hopefully that's not the problem, but I wouldn't rule it out.

Thanks in advance,
Aaron

[DazzleDiscus]

I don't have experience in this, but I think that posting pics will help those who do have experience be able to answer your question better

[froggsong]

My guess would be that you used too much of the additive and it's leaching out when wet and then drying on the outside. Please do post a pic if you can capture it on film well enough.

[Epiphile]

I mixed as per manufacturer's instructions- apparently it's able to be used undiluted, though I did dilute it progressively as I put more layers onto the piece.

From my reading yesterday I have a feeling that it's efflorescence causing the problem- a common predicament given the plethora of products designed to combat it. I'm going to just have to try and get the salts dissolved and scrub hell out of the piece and see what happens. Hopefully I won't have to resort to muriatic acid- a little unsettling...

Sorry I didn't manage to get a photo last night- I'll see if I can't get one soon.

[jchurch071]

I worked in the masonry field for several years. If it is salts causing your problem, the best way to solve it is to keep soaking in fresh water. Using hot water will allow the water to absorb more salts. Unfortunatly, it can be a long process removing all of the salt. If you can boil the piece and do it multiple times that would prob work the fastest. Be sure to change the water immediately after the water boils cause as the water cools it will begin to release the absorbed salts back to your piece.

[Epiphile]

That's the advice I was looking for- thanks.

Unfortunately the bit's about three feet long, so boiling's out of the question, but a hot shower's the route I think I'll go.

Thanks again- glad to hear I won't have to scrap the piece or resort to the stronger acids.