PPG Semkit Approved Mixing Techniques
PPG Aerospace sealants packaged in a Semkit® are approved to be mixed either by hand or by Semco Machine Mixer.
The mixing of a Semkit® by other means, such as with a drill adapter, may compromise the performance properties of the sealant and void the warranty.
When mixing a PPG Aerospace sealant Semkit®, always follow the directions as dictated on the product packaging. The recommended mixing instructions are tested and validated to ensure that the sealant performs as intended and meets all specification requirements. Instructions are provided for hand mixing (including Semco Model 285 mixer), or for automatic mixing with a Semco Model 388, Model 1088 or Model 1188 machine mixer.
Machine mixing and hand mixing are the only industry recognized methods for mixing sectionalized containers (Semkit®) as referenced in SAE AIR4069 and Boeing BAC5000. Mixing outside of these controlled and validated procedures has the potential to alter the sealant performance or even damage the sealant itself.
Testing shows that mixing with a drill adapter has several definitive detrimental effects on the sealant: Uncontrolled mixing speed will excessively heat the sealant and greatly reduce the working time of the sealant, and will decrease the extrusion rate below specification-required values. The high torque and shear induced with a drill may also damage certain raw material ingredients in the uncured wet sealant, irreversibly degrading the anti-sag properties of the wet sealant, or the density of the cured sealant.
Low density sealants are especially affected by drill mixing. Any of these negative effects may cause the sealant to perform outside of specification requirements, and will therefore void the certification and/or warranty. Mixing with a drill adapter also presents significant safety concerns, as there have been documented cases of user injury when mixing a Semkit ® with a drill.
Please see below video on PPG Semkit mixing techniques:
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