Quite a while since my original post and photo of discoloured pavers!
Yeah! 22nd of June.
After pulling up some discoloured pavers already laid, [ like about 35 - 400mm square] and replacing them with what looked good, we found that in 24 hrs or less they too developed the discolouration.
Company representative said "Lay them all, and we will come and clean the discolouration - called efflorescence - off them.
She's hard to get hold of - hit an answering machine 9 times out of 10. Anyway, finally told us they would come Tues 21st July.
Monday 20th - phone call from rep! Cleaning crew not able to leave Melbourne because of Covid 19 restrictions. !!!
Me " What is the cleaning process?"
Rep "Damp pavers, apply cleaning solution, wash off with plain water, apply detergent [to neutralise any remaining cleaner] then use a high pressure washer if necessary. Small area at a time."
Me "I've got a high pressure cleaner, supply me with the solution please. We want this job completed!"
Rep " Too risky to freight it - might leak!" then "I'll bring the cleaning solution to your local hardware [supplier of pavers]."
Me "Complete with FULL instructions? " " Yes"
Finally arrives Tuesday this week.
In the Paving co's glossy brochure, [detailing different colours, sizes etc.,] EXPLICIT instructions - DO NOT use acid to clean our products! Clear enough! What do they supply - ACID!
Product arrives - CORROSIVE Schedule 8 [nasty stuff] Nitric Acid 372 gm/Lt. Phosphoric Acid 140 gm/Lt
Instructions on label of two 5 lt containers. Dilute this product 1: 25 with water. Then apply as the Rep stated. Bottom line - DO NOT use stronger than 1: 15 with water !!!!!!!
OK !! Tried 1:25 on a 6 sq meter section [Total paved area is nearly 40 sq meters].
Allowed it to dry. Total effect - stuff all !! May as well spat on them!
Next section, tried 1:20 dilution. This, when applied, created some 'smoke' as in indicating a chemical reaction. Still no noticeable effect on the discolouration when they dried.
Cannot get the Rep on the phone.
Got a left over paver, badly discoloured, and tried the cleaning acid straight out of the bottle. That really reacted!! Result - even coloured, clean paver. But this 'etched' the surface a little.
Showed our local hardware guy. He said try as many as you want, find out what works!
Experiments show that 1:5 seems to work. 1:4 may be better and give the desired result.
Alternate is - Rip up the entire 40 sq mtrs, and do it all again. NOT AT MY EXPENSE !!
If I get the Rep on the phone next week, I want to talk compensation for -
1. Excess hours work for the paving laying contractor - hours extra!
2. All my stuffing around and hours of work I did not bargain on when we ordered the pavers.
Sorry for the long post - but that's the story [so far] I'll take photos before and after if I go ahead and clean them a second time! Keep you posted.