Stucco Hydration - Hydrating (Water Curing) Stucco (Preventing Soft Stucco Walls)

Sat, 01 Jun 2019 23:32:09 GMT

Hydration: The chemical reaction that occurs in Stucco when water is added and causes the liquid Stucco Paste to turn into a solid.

Stage 1 (Mixing)

Blending stucco in a mixer starts the hydration process.
Stucco should be mixed a minimum of 5 minutes (concentrate) or 3 minutes (premix) after all ingredients have been added (See mixing instructions on bag).

Empty the entire mixer after each batch.
All the particles in the mix are coated with water during mixing.
Soft stucco can result if the sand and stucco are not thoroughly mixed.
Over-mixing will entrain air and weaken the stucco.

Stage 2 (Application)

Stucco goes into a dormant stage after it is mixed.
The water coats the particles and cools the mix.
The stucco is now in a fluid (inactive) state and can be applied.
Stucco must be applied a minimum of 3/8 inches thick.
Stucco that is less than 3/8 inches thick will dehydrate easy and may not get hard.

Stage 3 (Hydration)

Stucco hydration begins once the water starts to dissolve the cement particles.
The temperature of the stucco will increase.
The dissolved cement particles start to form together.
The stucco begins stiffen and to form into a solid.

Stage 4 (Hydration/Curing)

Stucco must be kept moist for a minimum of 48 hours after application.
Stucco walls should be watered (fogged) in the morning and evening when the walls are cool.
Moist curing (watering) allows the hydration process to continue and the stucco to get hard.
Weather conditions (wind, heat, low humidity) may require more hydration (moist curing).
The hydration process stops if the stucco becomes dry and does not get re-hydrated.
The stucco may not get hard.
New (fresh) stucco that is dry can be re-hydrated.
Adding water to the dry stucco can restart the hydration process.
It is difficult to re-hydrate stucco after it is painted.

Potential Causes of Soft Stucco

Improper Mixing
Over sanding
Using out of spec sand or sand with excess silt (dirty sand)
Inadequate hydrating

Please see our printable flyer attached:

HydrationBulletinEnglishVersion062519.pdf

HydrationBulletinSpanishVersion062519.pdf

Stucco Curing Alert - Prevent Soft Stucco Walls

Sat, 01 Jun 2019 23:27:38 GMT

Attention Home Builder:

The heat of summer has arrived. Consequently, more effort must be made to insure that Stucco Walls are properly hydrated before they are painted. Soft stucco walls have been an ongoing problem in the Valley for several years. The hot summer months exacerbate the potential for problems. Please consider the following:

Stucco Hydration Facts

Water is the catalyst in the chemical process that causes stucco or cement-paste to crystallize and harden. It is not intended to reduce the stucco's pH.
Stucco Walls are required to be moist cured until the process that makes the paste set and harden is complete.
The time period required to cure and harden stucco varies with weather conditions such as wind, temperature and humidity.
More moist curing time is required during the hot and dry summer months.
Many stucco industry professionals recommend that stucco be allowed to cure 28 days before painting.
Once a stucco wall is sealed with paint, moisture can no longer get into the stucco and the curing process can stop.
A stucco wall that is soft at the time of painting will likely remain soft.

Recommendations (How Home Builders Can Help)

Allow ample time for your stucco walls to cure and harden before they are painted.
Consult with your Stucco Contractor regarding seasonal cure times.
Develop a protocol that insures stucco walls are not painted before they harden.

To learn more about the hydration and curing process, please email

executivedirector@arizonawallandceiling.com

Please find our flyer attached for your reference:

AWCIStuccoAlert7112019.pdf

AWCI-AZ Tech Specs

Stucco Hydration - Hydrating (Water Curing) Stucco (Preventing Soft Stucco Walls)

Stucco Curing Alert - Prevent Soft Stucco Walls