What can cause a difference in thickness of the basecoat plaster?Inward deflection of backing between framing members, improper alignment of framing members or out of level installation of exterior sheathing, masonry or concrete can cause a difference in thickness of basecoat plaster.
Should I offset joinings in scratch and brown coat?
Yes, joinings in brown coat should not occur at same place as joinings in scratch coat.
Should finish applications on one elevation be done with the same type of float?
Yes, all journeymen working on an elevation must use the same floating technique.
How long should the colour coat be mixed?
Mix every batch for a minimum of 10 minutes.
How do I prevent water from gutters and down spouts from causing pigment migration?
Ensure gutters and downspouts must be installed so water does not contact fresh coloured stucco. Diverter flashing installed at all trough and wall intersections on corresponding roof.
How do I prevent uneven drying on my basecoat?
Allow the brown coat to dry for five days after proper curing, longer if necessary in judgment of plastering contractor.
NOTE: Relatively longer drying is necessary: (1) when asbestos fiber is incorporated in scratch and brown coats as with gun applied plaster. (2) under unfavourable climatic conditions.
How do I apply popcorn (broom) dash texture?
First, apply a thin first coat to produce complete colour coverage, then use a stiff bristle broom to apply a second dash coat for texture depth and uniformity. When the first coat is dry, prepare mortar to a relatively stiff consistency. Load brush with mortar, shake off excess by banging on pail. Use same consistency for texture and colour coat.
How do I apply cold joints in brown coat?
Apply brown coat in continuous operation over entire panel or elevation, making any necessary stops at architectural breaks.
How can I prevent stucco stains on a building?
Ensure roofers, builders are educated to spot and repair all potential building problems that can lead to stucco stains, including repair improperly installed downspouts, applying a good waterproofing agent, using non–corrosive flashing and screed, sealing all wood adjacent to plaster and providing drainage for groundwater.
How can I prevent a difference in thickness of basecoat plaster?In line wire construction, care in lathing is required to provide a taut, straight base so that plaster may be applied to a uniform thickness. Inward deflection of backing between framing members should be kept to a minimum. Framing members should be aligned so the plaster membrane will be of uniform thickness while achieving a straight true surface and installed exterior sheathing, masonry, or concrete should provide a straight base for plaster of uniform thickness.
How can I correct colour variation?
Colour variation can be corrected by fog spraying or brush coating:
Fog Spraying: Mix factory–prepared brush coat with water to the viscosity of heavy cream, then dilute with water to milky consistency. Screen to remove any lumps. Pour into garden type or power sprayer. Apply over DRY surface in continuous passes until the entire wall has been covered completely. Use as fine a spray as possible and hold the nozzle at a uniform 90° angle to the surface to ensure even coverage. Spots may be “feathered out” when only a small portion of the wall shows discolouration. Allow overspray to dry, then wipe from trim with a Turkish towel.
Brushing Coating: Prepare wall by spraying with water lightly and evenly 30 minutes before application. Mix material as above and pour into bucket. Apply with a brush.
Does dash coat provide relatively consistent colour uniformity?
Yes, if properly applied.
Can over spraying of extraneous material such as paint, gypsum plaster, sealants, etc., cause non–uniform suction of the basecoat?
Yes. It is important that each coat of plaster must be kept clean of any materials which affect suction or density.
Can I proceed with colour coat application if the basecoat has moisture present?
No, do not proceed with colour application until the basecoat is dry.
Can I change brands of cement on panels or walls?
On each panel or wall only use a single brand of cement, otherwise non–uniform suction of the basecoat may result.
Can I add admixtures (e.g. lime, fire clay or soap) to IMASCO’s proprietary stucco colour coat?