Sag Control And Metallic Orientation
Two problems that share one cause: what the coating does in the sixty seconds after it leaves the gun.
Film build and metallic appearance are both decided by how fast the wet film recovers viscosity at rest. Too slow and it runs. Too fast and the aluminium flakes freeze at random angles. Six grades on this site work on that window, split between solventborne resins and waterborne additives.
Sag Control And Metallic Orientation In 6 Steps
Decide which failure you have
Sagging and mottling get treated as separate problems and fixed with additives that fight each other.
Sagging is a viscosity recovery problem. Mottling is an orientation problem. Several grades here address both, but the dosage that fixes one is not always the dosage that fixes the other.
Pick the right side of the fence
Solventborne and waterborne need completely different chemistry.
Solventborne: 904R, 906S and 908R sag control resins, plus QK4100 for anti-settling. Waterborne: QK8521 wax emulsion and QK8330 polyamide salt, plus QK4200.
Check what the structure size costs you
A coarse thixotrope buys sag resistance and loses gloss.
906S is below 10 microns, which is what makes clearcoat use possible. 904R and 908R are below 15 microns. Match the fineness to how the finish will be graded.
Account for reactivity
A sag control agent with hydroxy functionality changes the crosslink arithmetic.
908R carries an OH value of 100 mg KOH/g on solids and must be included in the NCO/OH calculation. 904R and 906S are not hydroxy functional.
Get the pH right in water
Waterborne orientation additives are acidic and will pull system pH down.
QK8521 requires system pH raised to 9-9.5 before addition, and more headroom as co-solvent content rises. QK8330 is slightly acidic and pre-blends with water at 4:1.
Measure it properly
A flow cup will not tell you anything useful about a thixotropic system.
Read final viscosity on a rotational viscometer. Grade sag on a sag bar at the target build, and grade orientation on sprayed panels under controlled light.
The Grades Referenced Above
Anti-Sagging Resin 904R
Urethane SCA for metallic automotive and industrial coatings, with unusually good CAB compatibility.
View technical data
Anti-Sagging Resin 906S
Fluid SCA at 58-62% solids for high quality automotive solid colours and clearcoats.
View technical data
Anti-Sagging Resin 908R
Hydroxy-functional SCA paste for two-component polyurethane automotive and industrial topcoats.
View technical data
QK8521 Waterborne Aluminium Pigment Orientation Agent
VOC-free EVA wax emulsion that lays aluminium and pearl pigment flat in waterborne basecoats.
View technical data
QK8330 Waterborne Rheology Control Agent
Modified polyamide salt that orients effect pigments and stops settling in waterborne automotive and industrial coatings.
View technical data
QK4100 Liquid Rheological Agent
Liquid polyurea thixotrope for solventborne and solvent-free coatings, PVC plastisol and air-drying resin systems.
View technical dataSag Control And Metallic Orientation Questions
Why will a flow cup not work here?
Which sag control agent is safe in clearcoat?
What pH does QK8521 need?
Start On Sag Control And Metallic Orientation
Send the formulation details and the constraint you are working against. A recommended starting point with the matching data sheets comes back by email.