GOLDEN GAC 100 Acrylic Fluid Medium, 473 ml — Extends Paint, Improves Flow & Film Strength

GOLDEN GAC 100 is a versatile acrylic fluid medium that extends acrylic paint while improving flow, control, and protection for supports.

GAC 100 is part of GOLDEN's line of acrylic fluid mediums and additives designed to expand what acrylics can do without changing their inherent film strength. Use it to thin colour for glazes, improve leveling for smooth passages, reduce the amount of binder needed for more intense pigment, or to pre-seal absorbent supports to reduce discoloration. Made in the USA by GOLDEN, this formula gives professional artists a predictable tool for adjusting viscosity, sheen, transparency, and dry behavior.

How does GAC 100 change the way acrylic paint behaves?

GAC 100 acts as a polymer extender that thins paint without weakening the acrylic matrix, preserving adhesion and film integrity while increasing flow. It allows you to make washes and translucent layers that sit smoothly on the surface, and it reduces the amount of binder needed, which can intensify colour when desired.

• Thins paint for transparent glazes and smooth spreads
• Improves flow and leveling for fewer brush marks
• Maintains film strength and adhesion when used in recommended ratios
• Can increase colour density by reducing binder concentration

Can I use GAC 100 to protect or prime supports?

Yes—applying two coats of GAC 100 to an absorbent support helps reduce Support Induced Discoloration (SID) and limits oil penetration when combining media. It forms a uniform, flexible layer that stabilises porous surfaces and improves the paint’s working properties on panels and papers.

• Two coats applied directly to supports reduce SID
• Creates an even, less absorbent surface for painting
• Helps block oil migration when using oil-based elements over acrylics
• Dries to a clear, flexible film compatible with acrylic systems

How should I mix and apply GAC 100 with acrylic colours?

GAC 100 mixes readily with acrylic paint; start with small ratios and increase to find the working properties you want. For transparent glazes use higher GAC 100 ratios, while for bodying or slight thinning use smaller amounts. Always test mixes and allow layers to fully dry before varnishing or overpainting.

• Stir gently before use for uniform consistency
• Adjust ratio depending on transparency and flow required
• Allow each layer to dry completely between coats
• Follow GOLDEN recommendations for maximum extender proportions

Will GAC 100 affect sheen or drying time?

GAC 100 can subtly influence surface sheen and the perceived drying behavior depending on how much is used and the pigments mixed with it. It is formulated to keep drying properties consistent with acrylic systems while offering artists control over final surface characteristics when combined with other GOLDEN mediums.

• May slightly alter sheen depending on concentration
• Works predictably within standard acrylic drying windows
• Compatible with other GOLDEN mediums to fine-tune finish and drying
• Does not compromise long-term film durability when used correctly

Who this is for: GOLDEN GAC 100 is aimed at professional and advanced hobbyist painters who want precise control over acrylic paint behavior—artists working in glazing, mixed media, panel and paper supports, and anyone needing a dependable, high-quality extender. If you want to improve flow, protect absorbent supports, or intensify colour without sacrificing film performance, GAC 100 is a practical studio tool.