Cement Coping: 2 x 4 Marks in the dried coping: how to remove them?

[Curlenjik]

Thanks for your advice.

The guys who installed the coping already tried to get those marks out -- they did a very light acid wash -- and nothing happened - you see them as they were.

On a separate test piece I tried TSP and that did not work - stained the piece even worse.

So you suggest:

1. Grout the coping
2. Put in the expansion joint between the coping and the deck pavers (which are in sand)
3. Use the pool for a season - even though the coping shows the alkalie marks as well after they are wet.
4. At the end of the season, then do a light acid wash again.

Is that about it?

Again, thanks for posting and for your advice.

[PoolDoc]

I'm not sure I'm ready to elevate my guesses to a full-blown suggestion.

I've seen marks like those 'age out' of concrete, but I don't have ANY understanding of exactly what causes those marks (I mean chemically; I know how to 'make' them), and I don't have the sort of experience that would allow me to say that what I've seen happen elsewhere, will happen to your pool.

If you can wait, wait. See if you get another answer from someone with more experience and more confidence in their answer.

I don't know if there's some sort of concrete forum on the Net; if there is, you might want to post there, because marks like these aren't unique to pools. You can use the links to the photos here. Since I put them on Picasa, it's not costing me anything for someone to download a meg's worth of image files.

If you do find an answer elsewhere, post it back here, if you don't mind.

[Curlenjik]

Will do and thanks again; if you hear of anything new, please pass it on to me. I'll read this column for the next couple of weeks, and again I thank you for taking the time to reach out and help.

S.

[PoolDoc]

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[Curlenjik]

My contractor had one spare coping piece sandblasted and that WORKED! So I am going to have the entire coping around the pool sandblasted and then stained to keep the alkalie from leeching through. Thanks for helping me noodle this problem.

[Curlenjik]

After sandblasting new concrete coping, what is the best sealer? A Lithium Sealer which is supposed to last 30 years, or a good sealer that lasts for 2-4 years. Is a Lithium Sealer good for Southern California outdoor, in the ground pool coping?