ANALISIS PENGARUH PERBEDAAN VARNISH TERHADAP STABILITAS TINTA FLEXOGRAPHY WATER-BASED

ABSTRACT
This final project aims to analyze the effect of different varnish types on the stability of water-based flexographic inks used in the packaging industry. Varnish is a key component in ink formulations, functioning as a binder, viscosity controller, and film-forming agent on printed substrates. The study was conducted at PT DIC Graphics by preparing four ink formulations: Light Formula with Varnish A, Light Formula with Varnish B, Medium Formula with Varnish A, and Medium Formula with Varnish B. Testing was carried out using an accelerated aging method at a temperature of 40°C for seven days. The observed parameters included viscosity measured using a Zahn Cup No. 3, color variation measured with a spectrophotometer using the ΔE 2000 method, rub resistance, and observations of ink homogeneity and sedimentation. The results indicated that different varnish types affected ink stability during storage. Varnishes that exhibited lower viscosity changes and lower ΔE 2000 values demonstrated better stability and were able to maintain print quality throughout the aging period. Therefore, the selection of an appropriate varnish is a crucial factor in improving the performance and quality of water-based flexographic inks.
Keywords: Flexographic Ink, Water-based Ink, Varnish, Ink Stability, Viscosity, ΔE 2000, Aging Time.

ABSTRAK
Tugas Akhir ini bertujuan untuk menganalisis pengaruh perbedaan jenis varnish terhadap stabilitas Tinta flexography water-based yang digunakan pada industri kemasan. Varnish merupakan komponen utama dalam formulasi tinta yang berfungsi sebagai binder, pengontrol viskositas, serta pembentuk lapisan film pada hasil cetak. Pengujian dilakukan di PT DIC Graphics dengan membuat empat formulasi tinta yang terdiri atas Formula Light Varnish A, Formula Light Varnish B, Formula Medium Varnish A, dan Formula Medium Varnish B. Pengujian dilakukan menggunakan metode accelerated aging pada suhu 40°C selama 7 hari. Parameter yang diamati meliputi viskositas menggunakan Zahn Cup No. 3, perubahan warna menggunakan spektrofotometer dengan metode ΔE 2000, ketahanan gosok (rub resistance), serta pengamatan homogenitas dan sedimentasi tinta. Hasil pengujian menunjukkan bahwa perbedaan jenis varnish memengaruhi stabilitas tinta selama penyimpanan. Varnish yang memiliki perubahan viskositas dan nilai ΔE 2000 yang lebih rendah menunjukkan kestabilan yang lebih baik serta mampu mempertahankan kualitas cetak selama aging time. Dengan demikian, pemilihan varnish yang tepat menjadi faktor penting dalam meningkatkan performa dan kualitas tinta flexography water-based.
Kata Kunci: Tinta Flexography, Water-based Ink, Varnish, Stabilitas Tinta, Viskositas, ΔE 2000, Aging Time.