Streaking in low sheen finishes
Streaking or uneven sheen is a phenomenon which almost always appear in Satin and/or Semi-Gloss finishes both solvent borne and water borne products. It has long been thought that this may be caused by flatting or dulling agents having either not been stirred well or having settled prematurely. It is rare for flatting agents to settle out during the coating of the average floor job. If not stirred sufficiently the floor would probably show up glossier at the start and duller when the coating ends.
It is my opinion that most uneven sheen or streaking problems are caused by “uneven application” of a satin or semi-gloss finish. This condition has been more obvious since the VOC laws caused the solid content of products to go up and solvent content to go down. These conditions cause oil products to lose flow and leveling characteristics.
For explanation purposes let us assume that gloss, semi-gloss and satin finishes all start with the same base material. Flatting or dulling agents are added to the gloss product to reduce the sheen and create satin, super satin and semi-gloss sheens. If it takes “x” amount of flatting agent to make semi-gloss it may then take “2x” or twice as much to make satin and maybe “2.5x” to make a duller product. When we stir satin it takes more work than stirring semi-gloss. When dispersed throughout the coating and applied to the floor the flatting agent settles to the bottom of the film and creates the desired sheen level. If the coating is applied evenly the thickness of the film over the flatting agent will refract the light evenly and produce a uniform sheen level. If the coating is uneven, the sheen level will be higher where there is a large drop of finish, applicator marks or a puddle in the finish. Where the film is thinner the sheen level will be lower. When the film is uniform the sheen level will be uniform.
When oil finishes are applied with lambswool applicators, either mopped back and forth or dragged across the floor all thicker areas will show up as shiny streaks while thinner areas will appear duller. The same is true when waterborne products are mopped or dragged with either a lambswool (not recommended) or a rectangular paint pad. Thicker products or heavy applications will show this condition. In my opinion, weighted T-bar applicators work best.
Older oil products did not have this problem since most were 36 to 42 percent solids compared to todays products which are 50 to 60 percent solids. So a little extra time spent applying a uniform coating will be rewarded with a uniform sheen level across the floor.
Streaking or uneven sheen is a phenomenon which almost always appear in Satin and/or Semi-Gloss finishes both solvent borne and water borne products. It has long been thought that this may be caused by flatting or dulling agents having either not been stirred well or having settled prematurely. It is rare for flatting agents to settle out during the coating of the average floor job. If not stirred sufficiently the floor would probably show up glossier at the start and duller when the coating ends.
It is my opinion that most uneven sheen or streaking problems are caused by “uneven application” of a satin or semi-gloss finish. This condition has been more obvious since the VOC laws caused the solid content of products to go up and solvent content to go down. These conditions cause oil products to lose flow and leveling characteristics.
For explanation purposes let us assume that gloss, semi-gloss and satin finishes all start with the same base material. Flatting or dulling agents are added to the gloss product to reduce the sheen and create satin, super satin and semi-gloss sheens. If it takes “x” amount of flatting agent to make semi-gloss it may then take “2x” or twice as much to make satin and maybe “2.5x” to make a duller product. When we stir satin it takes more work than stirring semi-gloss. When dispersed throughout the coating and applied to the floor the flatting agent settles to the bottom of the film and creates the desired sheen level. If the coating is applied evenly the thickness of the film over the flatting agent will refract the light evenly and produce a uniform sheen level. If the coating is uneven, the sheen level will be higher where there is a large drop of finish, applicator marks or a puddle in the finish. Where the film is thinner the sheen level will be lower. When the film is uniform the sheen level will be uniform.
When oil finishes are applied with lambswool applicators, either mopped back and forth or dragged across the floor all thicker areas will show up as shiny streaks while thinner areas will appear duller. The same is true when waterborne products are mopped or dragged with either a lambswool (not recommended) or a rectangular paint pad. Thicker products or heavy applications will show this condition. In my opinion, weighted T-bar applicators work best.
Older oil products did not have this problem since most were 36 to 42 percent solids compared to todays products which are 50 to 60 percent solids. So a little extra time spent applying a uniform coating will be rewarded with a uniform sheen level across the floor.
<< Home