Are regular black, white and grey paints diffirent from paints labeled as “Primer”? Can I use paints like white,black and grey as a primer? Or will using paints specifically labled as a primer work differently?
In: 7
Primer is a special kind of paint that serves 3 main functions:
1) Helps paint stick to the surface. Some surfaces like metal or ceramics can be very ‘slippery’ and difficult for the paint to stick to. Primers acts as a sort of glue to help the paint adhere properly to the surface.
2) Prevents paint absorbing into the surface. Things like bare plasterboard or bare timber will absorb the paint, which can lead to a very blotchy and uneven finish. Primer acts to as coating to block the paint from soaking into the surface.
3) Prevents dark colours leaching through a light topcoat. If you paint (say) white paint over an existing black surface, you’ll often see the old black still visible the new white paint. Primer acts as a blocker to prevent the previous darker colours from coming through.
Chemically, primer is paint that is specifically formulated for its adhesive and blocking properties. Because it is NOT designed to be the main topcoat, it is not formulated to be ‘pretty’ and hard-wearing (in fact, most primer has a dull appearance and chalky texture).
So no, you cannot use standard paint as a primer, as it won’t do the job of primer very well. And you can’t use primer as the topcoat, as it (a) doesn’t look very nice, and (b) will quickly chip and flake away once exposed to the elements.
Primers are specifically formulated to
1. bond tightly to the surface.
* help paints adhere to the primer.
This means a coat of paint over a coat of primer is usually more durable than the same coat of paint directly on the surface, which if you’re doing painting for the maintenance benefit is a big deal. If you’re doing painting for decoration, it still helps flimsier paints look their best.
Coatings chemist here:
Primers are different from topcoat layers in a couple ways depending on what you are coating.
Adhesion – primer on surfaces like walls or tool boxes or plastic substrate are made to promote adhesion to that material.
Hiding – primers typically are formulated to have higher pigment weight content. This means they hide the color that is below them. This allows your pretty topcoat colors to keep their true color.
Water resistance – typically industrial coatings and automotive coating primers are layers that protect the substrate from water. This is particularly useful for any coating over metal to protect from oxidizing your metal.
Impact resistance – industrial, automotive or coil coating primers typically are formulated with an epoxy resin that helps act as a miniature spring. This resists any impact damage from stones, tools or other hard objects that may contact it.
Appearance – primers are your first layer to positively contribute to a nice appearance.
Let me know if you have any other coatings related questions.
Yes, Aluminium etch primers chemically react and bond to the substrate. Copper Boat Primer bonds to the wood, and stops mould. Internal paints are not so fussy, I often use White Emullsion as a wood primer indoors. Steel needs a primer made for steel. Aeroplanes need special primers. I have literally seen four coats of paint slowly roll off a wing as the surface was not degreased and etch primed first. It nearly cost the company a few million pounds in lost contracts.
Latest Answers