Stucco Recipes for the Mortar Sprayer

Stucco Recipes for the Mortar Sprayer
September 13, 2014
Sammy

Choosing the right tools can help a project for speed and ease, We have the correct stucco recipes & variations for the Mortar Sprayer. As a stucco sprayer can be many times faster than the old hawk & trowel. Read more

By Herb Nordmeyer

Each method of application of stucco requires a little fine tuning of the formula to get the optimum results. Here are some starting formulae for using the Mortar Sprayer for several different stucco applications. Sand is variable, and you have to live with what is available, thus these are referred to as starting formulae. The best blended stucco mix I have ever worked with is the Magna Wall Brand, but it is not available in many parts of the country. This document deals with products that are available.

Most stuccos have a water/cement ratio of about 0.55. With most mixes FritzPak Supercizer 7 (a dry water=reducing agent) can be added to reduce the W/C ratio to about 0.4 and increase the strength. If FritzPak Supercizer 7 is not available, use FritzPak Supercizer 5. The down side is these agents have a limited working time in the stucco (about 20 to 30 minutes). FritzPak Supercizer 7 comes prepackaged in 2.5 pound (40 ounce) bags. Recommended dosage rate is from 4 to 12 ounces per bag of Portland Cement. Polycarboxolate water-reducing agents have a much longer working time, and can reduce the W/C ratio down to about 0.32, but they are harder to find in small quantities and tend to make the mixture slick. This necessitates spraying a number of thin layers.

Fibers Stealth or Stealth imitator fibers (6- to 7-deneir polypropylene fiber) are the most efficient fiber to use. Normal dosage rate is 1.5 ounces per bag of Portland Cement for normal stucco applications and not more than 4 ounces per bag for FerroCement and Panel mixes. Higher dosage rates can reduce the compressive strength.

Stucco Sprayer for Walls

The Tirolessa USA Stucco Sprayer can be used for applying plaster, shotcrete, papercrete, earthen mixes, plastering a stucco house, traditional one coat or three coat stucco, GFRC, stamped concrete, stucco fences, organic sculptures, and more! learn more

Scratch Coat Stucco on Lath

  • 1 bag Portland Cement 94 lbs
  • 0.33 bags Type S Hydrated Lime 16 lbs
  • 4 cubic feet of loose damp plaster sand 5.33 5-gallon buckets

This will produce a 2,700 to 3,200 psi mix. Moist cure for 48 hours before adding Brown Coat.

Brown Coat Stucco on Lath

Use the Scratch Coat Stucco formula and increase the Hydrated Lime and the Sand by 10%. This will make a weaker mix so as it dries, it will not crack the scratch coat. Moist cure for 48 hours and dry cure for 5 days before adding the finish coat (reduces the tendency to effloresce).

Finish Coat Cementations Stucco – Traditional cement stucco mix

  • 1 bag White Portland Cement 94 lbs
  • 0.5 bags Type S Hydrated Lime 25 lbs
  • 5 cubic feet of loose damp sand 6.67 5-gallon buckets

Depending on the texture desired, different gradations of sand may be used. Pigment may be added. Add pigment with the initial water and sand so it can disburse evenly in the mix.

Panel and Dome Construction

  • 1 bag Portland Cement 94 lbs
  • 1 oz Liquid KelCrete Admixture 1 oz
  • 3 cubic feet of loose damp sand 4 5-gallon buckets

This will produce a 3,500+ psi mix, but it will not be as workable as the stucco mixes above. Crushed sand will produce greater strength and will not be as workable.

FerroCement

  • 1 bag Portland Cement 94 lbs
  • 1/5th bag Type S Hydrated Lime 10 lbs (Or 1 ounce of KelCrete)
  • 12 ounces of FP Supercizer 7
  • 3 cubic feet of plaster sand 4 5-gallon buckets

FerroCement is applied to an armature of 5 or more layers of wire or mesh. To get good penetration, it needs to be sprayed into the mesh and worked from one side until the armature is full of stucco and then worked from the other side until that side of the armature is full of stucco. If gaps are left in the armature, there will always be a weak spot. Mix should be as thick as possible while being able to work it into the armature.

Carving Plaster

  • 1 bag Portland Cement 94 lbs
  • 0.5 bags Type S Hydrated Lime 25 lbs
  • 3 cubic feet of loose damp 60 mesh sand 4 5-gallon buckets

This is a high-build, high-plastic stucco. As it dries, it can be carved. Adding most additives will shorten the working time. This stucco weighs 1.5 pounds per square foot per 1/8 in thickness.

Light-Weight Carving Plaster

As per Carving Plasters instructions, but perlite can be used to replace up to 100% of the sand. If you can find it, use perlite that is approximately 60 mesh. With full perlite substitution, this stucco can weight as little as 0.375 pounds per square foot per 1/8 in thickness.

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