# Painting doors, windows and wood: preparation, enamel, varnish and iron

> How to prepare wood and iron, the difference between enamel, varnish and lasur, and how long to wait between coats, per CIN, Robbialac and Barbot data sheets.

- Page: https://paredecerta.pt/en/guides/painting-wood-doors-and-windows
- Language: English
- Updated: 2026-11-04

## Summary

- Preparation decides: dry wood, sanded along the grain and primed or undercoated before the enamel.
- CIN sheets give 6 hours between coats of water-based enamel and about 24 hours for the synthetic primer; Robbialac gives 24 hours for its synthetic enamel.
- On iron, CIN has a water-based enamel applied directly without primer, once loose rust is gone. Reinforce the coat on edges.
- Old paint may contain lead: read the lead guide before sanding or scraping.

Doors, windows and railings paint badly when the preparation is short. This guide uses CIN, Robbialac and Barbot data sheets to explain how to prepare wood and iron, what separates enamel, varnish and lasur (wood stain), and how long to wait between coats. It does not compare brands.

*Updated on 4 November 2026. General information; it does not replace a technician's assessment or the data sheet of the product you buy.*

## The essentials

- **Preparation decides the result.** Dry, clean wood, sanded along the grain, with a primer or undercoat.
- **Water-based paint, synthetic enamel, varnish and lasur are different things.** Enamel hides the wood; varnish and lasur let it show.
- **Iron must be free of loose rust** before any paint. CIN sells a water-based enamel applied straight onto iron; other sheets ask for a primer.
- **Old paint may contain lead.** See [old paint and lead](https://paredecerta.pt/en/guides/old-paint-lead-sanding-safety) before sanding.
- **Times change from sheet to sheet** (6 to 24 hours between coats). The sheet of the product you buy rules.

## Enamel, varnish or lasur

| Type | What it is for (per the sheet) | Data read |
|---|---|---|
| **Water-based enamel** (CIN AC-Thane Satinado 12-260, June 2025) | Wood or metal, interior and exterior | 2 to 3 coats, 13 to 15 m²/L per coat, recoat after about 6 h, VOC up to 115 g/L |
| **Synthetic enamel** (Robbialac Viplux Brilhante, no date on the sheet) | Wood or metal, after suitable primers | 2 coats, 10 to 13 m²/L, 4 h to dry and 24 h for the next coat, VOC up to 299 g/L |
| **Interior varnish** (CIN Movidur Super Acetinado 12-330, September 2020) | Doors, furniture, interior wood | 12 to 14 m²/L, touch-dry in about 45 min |
| **Exterior varnish** (CIN Marítimo Super 12-310, February 2016) | Exterior wood | 2 to 3 coats, recoat after 8 to 10 h |
| **Lasur** (CIN Lasur Super Satinado 12-355, September 2020) | Decorative protection of wood, interior and exterior | 2 to 3 coats, about 15 m²/L |

Barbot has a water-based enamel for walls, wood and metal (1100 In & Out Brilhante, sheet of 16 December 2024): 12 to 15 m²/L, VOC 24 g/L. See also [paint types](https://paredecerta.pt/en/guides/paint-types-emulsion-acrylic-enamel).

Viplux contains solvent: flash point 23 to 61 °C (Robbialac). Ventilate and read the safety data sheet.

## Preparing wood

**New wood**

1. Check it is dry. CIN asks for wood moisture between 8 and 12%; Barbot, below 18 to 20%. Follow the sheet of your product.
2. Remove dust and grease and sand along the grain with medium-grit paper (CIN).
3. Apply primer or undercoat. CIN says two coats of its Acrylic Wood Primer/Undercoat (11 to 13 m²/L, recoat after 4 to 6 h). If you want it to block tannins, always two. For woods that bleed a lot of tannin, the AC-Thane sheet names Aqua Primer.
4. With knots, CIN does not recommend the water-based enamel (resin may bleed) and warns that the primer may not block it there.

**Wood already painted**

- **Paint in good condition:** sand and wipe with synthetic thinner to remove grease and maintenance products. One coat of primer is enough (CIN). Robbialac asks for cleaning with diluted detergent and a pass of fine sandpaper.
- **Paint in poor condition (peeling):** scrape back to the wood or use a heat gun, then treat as new wood (CIN). Robbialac says paint stripper, a putty knife and rubber gloves.
- **Fungi and algae:** Barbot says wash and disinfect with its own solution, neutralise with water, dry well, and only then protect and paint.

In old houses, scraping and stripping disturbs old paint: the rules on dust and heat guns are in the lead guide.

## Iron, railings and gates

- **Loose rust:** brush with a wire brush or sand until it is gone. CIN says the surface must be free of poorly adhering rust and mill scale.
- **Enamel straight onto iron:** CIN DT-Metal Liso 12-280 (April 2026) goes directly onto iron without primer. It asks for 2 to 3 coats, 90 to 100 µm dry film, 9 to 11 m²/L. It warns that the film is thinner on edges and corners and may fail early: reinforce them.
- **With primer:** AC-Thane uses one coat of quick-drying primer or acrylic metal primer. Robbialac names an anti-rust primer.
- **Aluminium and galvanised steel:** acrylic metal primer (CIN). Barbot says to sand galvanised steel carefully so as not to remove the zinc.
- **Heavy rust:** Barbot says strip, use an anti-rust product, and apply a rust converter on any remaining spots.

## Step by step

1. Protect glass, ironmongery and walls.
2. Sand, remove dust and degrease.
3. Primer or undercoat, for the time on the sheet.
4. Lightly sand the undercoat (Robbialac and Barbot ask for another sanding).
5. Enamel: 2 coats. AC-Thane takes both coats on the same day, about 6 hours apart (20 °C, 60% relative humidity).
6. Varnish and lasur: sand with fine grit between coats (CIN). Round off sharp edges for varnish.
7. Follow the sheet's time before using the window or door again.

## Times and conditions

| Product | Touch-dry | Next coat | Sheet conditions |
|---|---|---|---|
| AC-Thane (CIN) | about 30 min | about 6 h | above 5 °C, relative humidity below 80% |
| Acrylic Wood Primer/Undercoat (CIN) | about 1 h | 4 to 6 h | above 5 °C |
| Synthetic primer (CIN 18-055) | 2 to 3 h | about 24 h | above 5 °C |
| Viplux (Robbialac) | 4 h | 24 h | between 5 and 35 °C |
| Marítimo Super (CIN) | 1 to 3 h | 8 to 10 h | relative humidity below 70% |

CIN asks for the surface to be 2 to 3 °C above dew point, with no direct sun and no rain forecast. See [best time of year to paint](https://paredecerta.pt/en/guides/best-time-of-year-to-paint).

## Interior or exterior

- **Exterior:** Marítimo Super asks for maintenance at the first sign of change, never later than 3 years, with a light sanding and 1 or 2 coats. Clear varnish does not protect some woods (walnut, afzelia) from colour change by light.
- **Lasur:** CIN warns that durability falls on damp wood (above 12%), without fungicide or insecticide treatment, and on south or south-west faces, horizontal surfaces or edges. Water-based varnishes and lasurs are not for dense, closed-grain woods; for ipe or teak, CIN names only teak oil.
- **Interior:** Movidur is meant for doors and furniture, with good resistance to household cleaning products (CIN).

## What we could not confirm

- **Durability in years** of enamels on exposed windows: the sheets do not give it.
- **The date of the Viplux sheet:** the copy we read does not show one.
- **Maximum wood moisture:** 8 to 12% (CIN) against below 18 to 20% (Barbot). We found no independent standard.
- **Price of painting doors and windows:** see [cost of painting a house](https://paredecerta.pt/en/guides/interior-painting-cost).
- **Sheets from other brands** (Dyrup, for example): not read.

## Sources (read on 4 November 2026)

- CIN, technical bulletin AC-Thane Satinado 12-260, revision June 2025 (https://idoctec.cin.com/Home/Document/12260-DEC-SOT-BT-PT). Read in full.
- CIN, technical bulletins Prim. Subcapa Acrílico Madeira 18-050 (https://idoctec.cin.com/Home/Document/18050-DEC-SOT-BT-PT) and Primário/Subcapa Sintético Madeira 18-055 (https://idoctec.cin.com/Home/Document/18055-DEC-SOT-BT-PT). No visible revision date. Read in full.
- CIN, technical bulletin DT-Metal Liso 12-280, revision April 2026 (https://idoctec.cin.com/Home/Document/12280-DEC-CIN-BT-PT). Read in full.
- CIN Woodtec, bulletins Movidur Super Acetinado 12-330 (September 2020), Lasur Super Satinado 12-355 (September 2020) and Marítimo Super 12-310 (February 2016) (https://idoctec.cin.com/Home/Document/12330-DEC-SOT-BT-PT, .../12355-DEC-SOT-BT-PT, .../12310-DEC-SOT-BT-PT). Read in full.
- Robbialac, data sheet Viplux Brilhante (https://tintasrobbialac.pt/download/ficha_tecnica/ROB_V68/1/Viplux+Brilhante-ficha_tecnica.pdf). No visible date. Read in full.
- Barbot, data sheet 1100 In & Out Brilhante, 16 December 2024, rev. 9 (https://barbot.pt/wp-content/uploads/2024/01/1100-FT-ESMALTE-IN-AND-OUT-Rev.-8.pdf). Read: properties, wood and metal paint systems.
- Guide in this series on lead and heat guns: [old paint and lead](https://paredecerta.pt/en/guides/old-paint-lead-sanding-safety).

## FAQ

### Do I need a primer to paint wood?

CIN sheets ask for two coats of undercoat on new wood and one on previously painted wood. Barbot also asks for a water-based undercoat, with sanding before and after.

### How long do I wait between coats of enamel?

CIN gives about 6 hours for AC-Thane (20 °C, 60% relative humidity). Robbialac gives 24 hours for its synthetic enamel Viplux.

### Can I paint iron without a primer?

CIN says DT-Metal Liso goes directly onto iron without primer, once loose rust is removed. Other sheets ask for an anti-rust primer.

### What is the maximum wood moisture?

CIN asks for 8 to 12%. Barbot gives below 18 to 20%. Follow the sheet of your product.

---
Source: https://paredecerta.pt/en/guides/painting-wood-doors-and-windows. Independent information, not legal or tax advice.