The most common wallpaper defects are caused because the walls have not been lined. Lining paper makes the wall surface smooth and even and provides the correct amount of porosity to ensure maximum adhesion when the wallpaper is hung over it. Lining paper comes in different qualities and weights, so select the one that is right for your wallpaper. Hanging lining paper horizontally ensures that no joins will align with the joins in the wallpaper, which is hung vertically.
If your walls are very uneven or have fine, hairline cracks, then hanging a double lining – the first vertically and the second horizontally – will smooth out the walls. You can also line a wall prior to painting it – a good idea if the previous paint was a dark colour. The lining will obliterate it so that the old colour does not adversely affect the new colour or bleed through. Hang the lining paper vertically in this case, as you would hang wallpaper; that way the joins will be fewer and less visible when painted.
Keep the room well ventilated when you are painting and don’t allow any naked flames nearby.
If you accidentally splash paint in your eyes, rinse them with lots of cool water. Consult a doctor if the irritation persists.