2K Acrylic Primer 4:1: Mixing and Application

Short answer: AKRİLİK ASTAR 2K – 4:1 is prepared by adding one part of the hardener AKRİLİK SERTLEŞTİRİCİ to four parts of primer. If needed, it is thinned with AKRİLİK TİNER (acrylic thinner) by up to 20% by volume, and the mixture is used within 4 hours at 25 °C. According to the values given in the data sheet for 2 coats and 50–60 µm, the primer can be sanded after drying for 3 hours at 20 °C or 30 minutes at 60 °C. After sanding, the next coat must be applied within 12 hours at the latest.

The values below are taken from the technical data sheets of AKRİLİK ASTAR 2K – 4:1, PLASTİK ASTAR 1 K and ACRYLIC VERNISH 2K.

What is AKRİLİK ASTAR 2K – 4:1?

AKRİLİK ASTAR 2K – 4:1 is a two-component, acrylic-based surface primer developed to give a smooth, even surface before the topcoat. According to its data sheet, it provides surface integrity and fast drying in repair areas, adheres strongly to the substrate to protect against corrosion and forms a base for the topcoat that follows. Suitable substrates:

• OEM paints
• Previously painted surfaces
• Metal surfaces such as steel, galvanized steel, stainless steel and aluminum

Plastics are not on the data sheet's list of substrates. Plastic parts such as bumpers get a separate plastic primer (see below).

Technical values

Property	Value
Number of components	2
Mixing ratio (primer : AKRİLİK SERTLEŞTİRİCİ)	4 : 1
Pot life (25 °C, after adding the hardener)	4 hours
Thinner	AKRİLİK TİNER, up to 20% by volume
Mixed density (20 °C, TS EN ISO 2811-1)	1.70 ± 0.02 g/cm³
Viscosity, A+B (EN ISO 3219)	2000–2500 mPa·s
Solids content (TS EN ISO 3251)	80 ± 2%
Drying before sanding (2 coats, 50–60 µm)	3 hours at 20 °C · 30 minutes at 60 °C
Maximum waiting time after sanding before the next coat	12 hours
Shelf life (unopened packaging, 20 °C)	1 year
Packaging	1 L and 5 L metal cans

How is the 4:1 mixture prepared?

4:1 means four parts of primer to one part of hardener: for example, 100 units of AKRİLİK SERTLEŞTİRİCİ are added to 400 units of primer, giving 500 units of mixture. The data sheet gives the ratio as 4:1 but does not state whether it is by volume or by weight; the data sheet of the clear coat used with the same hardener, by contrast, clearly gives its ratio by volume. Confirm this with our technical team before choosing a graduated cup or a scale.

1. Shake the primer thoroughly before use.
2. Mix the primer and AKRİLİK SERTLEŞTİRİCİ at a ratio of 4:1.
3. If needed, thin with AKRİLİK TİNER by no more than 20% by volume. The data sheet does not name any other thinner.
4. Use the mixture within 4 hours at 25 °C. In practice, only as much mixture is prepared as can be used up within this time.

Application steps

1. Surface preparation: sand the surface properly to remove all corrosion and rust; remove dust, oil and dirt completely.
2. Equipment: remove all moisture from the painting equipment before use.
3. Mixing and thinning: mix the primer 4:1 and, if needed, thin it with AKRİLİK TİNER by up to 20% by volume.
4. Application: the drying values in the data sheet are given for 2 coats and 50–60 µm. If the coats are applied very thick, drying may take longer.
5. Drying and sanding: sand the primer after drying it for 3 hours at 20 °C or 30 minutes at 60 °C.
6. Next coat: apply the next coat within 12 hours of sanding at the latest.
7. Cleaning: clean the equipment thoroughly immediately after application and close the can tightly.

The data sheet gives drying times only for 20 °C and 60 °C; it does not state an ambient temperature or relative humidity range for application. In practice, drying takes longer as the temperature falls. In cooler conditions, set the sanding time together with our technical team.

On plastic parts: PLASTİK ASTAR 1 K

For PP-EPDM bumpers and ABS vehicle parts, PLASTİK ASTAR 1 K is used. This one-component, acrylic-based, gray primer provides adhesion on plastic surfaces; according to its data sheet, primers and topcoats can be applied over it.

Step	Value in the data sheet
Cleaning	Washing with warm water and a suitable detergent, rinsing with clean water; a suitable cleaning thinner for remaining dirt and grease
Abrading	Red or gray scuff pad on PP-EPDM and ABS parts, followed by cleaning thinner again; on painted thermoplastic parts, final dry sanding with P220–P320 and P400 for spot repair edges
Number of coats and film	1 coat (2 if desired); 15–20 µm dry film per coat; each coat over a wider area than the previous one
Touch dry (20 °C)	20–30 minutes
Flash-off before primer or topcoat (20 °C)	30 minutes
Maximum waiting time for primer or topcoat (20 °C)	24 hours; if exceeded, the surface is sanded with a gray scuff pad and 1 full coat is applied again

Surfaces with body filler must not come into contact with water or water-based cleaners. If AKRİLİK ASTAR 2K – 4:1 is to be applied over the plastic primer, confirm the system with our technical team.

After the primer: topcoat and clear coat

The topcoat is applied over the sanded primer within 12 hours at the latest. In basecoat systems, ACRYLIC VERNISH 2K, used as the clear coat, is applied over a fully dried and cleaned basecoat. The clear coat is also mixed with AKRİLİK SERTLEŞTİRİCİ, but at 2:1 by volume, and its pot life is 5 hours at 25 °C. As the ratios differ, prepare the primer and clear coat mixtures in separate, labeled cups.

Information not in the data sheet

The data sheet of AKRİLİK ASTAR 2K – 4:1 does not include the following. Instead of working on assumptions, ask our technical team:

• Ambient and surface temperature and relative humidity range for application
• Flash-off time between coats
• Spray gun nozzle size and pressure
• Sandpaper grit for sanding the primer
• The unit of the mixing ratio (volume or weight)

Frequently asked questions

What does 4:1 mean for a 2K primer?

It means that one part of hardener is added to four parts of the two-component primer. With AKRİLİK ASTAR 2K – 4:1, the hardener is AKRİLİK SERTLEŞTİRİCİ.

How much thinner can be added to the 2K primer?

It is thinned with AKRİLİK TİNER by no more than 20% by volume. The data sheet does not name any other thinner.

How long can the mixed primer be used?

After the hardener is added, the pot life is 4 hours at 25 °C. In practice, mixture older than this is not used.

When can the 2K primer be sanded?

According to the values given in the data sheet for 2 coats and 50–60 µm, after 3 hours at 20 °C or 30 minutes at 60 °C. If the coats are applied very thick, this may take longer. After sanding, the next coat must be applied within 12 hours at the latest.

Can it be applied to galvanized steel, aluminum or plastic?

According to the data sheet, AKRİLİK ASTAR 2K – 4:1 is applied to metal surfaces such as steel, galvanized steel, stainless steel and aluminum, to OEM paints and to previously painted surfaces. For PP-EPDM bumpers and ABS parts, PLASTİK ASTAR 1 K is used.

For clear coat application mistakes and how to avoid them, see Common Mistakes in 2K Clear Coat Application.

Tell us the surface to be repaired (steel, galvanized steel, aluminum, plastic or old paint), your workload and your drying options (ambient temperature or a 60 °C bake booth) in the quote form, and our technical team will recommend a suitable primer and clear coat system. For all primers, see the car repair primers page.