One of the final steps in any wet-set project is the final acid wash-down, which is what I’d like to focus on for this week’s post.
I won’t get into details on the entire wet-set installation process, as I’ve documented that process in previous posts. But once the bulk of the installation is complete, there is one final step to achieve the final desired results, and that is the final acid wash.
The wet-set procedure, as previously stated, involves setting the stones atop a concrete slab in a bed of mortar. And if you’ve ever worked with mortar before you know it can be messy and involves a fair amount of clean-up as the process unfolds. The stones are set in the mortar bed and the joints between the stones are “pointed”, or filled in with mortar to achieve a continuous surface.
But as the stonework is pointed, a chalky white residue is left behind even after the bulk of the mortar has been cleaned up and finished. And that chalky residue can seriously detract from the true look and color of the natural stones.
So how does that white residue get cleaned up? That is where the acid wash-down comes in.
Simply wet down the surface, dilute the solution with water – usually about a 6-to-1 ratio of water to acid, but sometimes slightly stronger depending on the degree of residue – and lightly scrub off the residue.
As the acid solution is applied to the surface you will see some minor bubbling and sudsing as the acid wash reacts with the alkaline film. As it reacts it lifts the white stains off the stones and can be rinsed off quite easily with one final rinse-down. Some light scrubbing assists the process along and helps to clean some of the small nooks and crannies of textured stones. But fear not – this is not heavy elbow grease, just some light scrubbing to assist the process along. Once the entire surface is cleaned and rinsed, and the surface has time to dry you will see a noticeable difference as the true look of the natural stones returns.
A few quick other notes -- the acid wash should not be in lieu of cleaning up the mortar as the stones are installed. As stated, the 600 wash is a mild cleaner, designed to be environmentally friendly and relatively harmless to adjacent plants or lawns. But because of its mild formula it won’t remove large mortar chunks that have adhered to the stones or were left uncleaned while the mortar was still soft. Joints and stones should still be finished appropriately during the installation and sponged off as much as possible. The wash is simply designed to lift the remaining chalky film.
And yes, other cleaners are available. For those of you familiar with masonry installation, you may be familiar with the traditional muriatic acid cleaner. And if you’re familiar with muriatic, then you know it can be nasty stuff. Many safety precautions need to be taken with muriatic, as it can burn through skin, clothing, and even buckets if not mixed properly. And the fumes can be quite harmful if not used in a well-ventilated space.
And while some basic safety precautions should still be taken even with the 600 wash, particularly if not diluted properly, it is quite mild and not nearly as hazardous to work with. And if due diligence was adhered to during the main bulk of the installation, the 600 wash will achieve the desired results. And you will be ready to enjoy your new hardscaping at its full beauty for years to come!