What comes first primer or bondo?

The opinion by a large amount was to put epoxy primer down on bare clean metal first and the filler next. Southern Polyurethanes which makes high quality primers that are used by quality restoration shops says to use their epoxy primer before bondo.

Can you put bondo over primer?

True. You CAN apply over sanded 2k primer, or bare metal. Be sure to have the area sanded with at least a 150 so the filler has some TOOTH to grab to. I usually fill over 80 grit.

What should I do before bondo?

Before you begin applying Bondo, make sure to sand down the paint, replace any rusted metal, and mask off any areas that don't need filler. After that, you're ready to apply the bondo and fix any small scratches and dings!

Do you apply primer before body filler?

For small repairs, you can bog directly over the bare metal. If the repair is larger, or you're looking for a longer-lasting job, apply a base coat of epoxy primer before laying on the filler.

Can you Bondo over rust?

To Bondo or Not to Bondo

Minor surface rust can often be sanded and painted, but major rust pitting and holes may require a little more effort and material — specifically, Bondo or some other quality body filler. However, Bondo shouldn't be used on every kind of rust hole.

Filler over primer? The proper way it can be done

How long should Bondo dry before sanding?

When used according to the manufacturer's recommendations, Bondo takes 10 to 15 minutes to dry enough to form a sandable surface. After 45 minutes it's cured enough to be painted.

How do you prepare metal for bondo?

Before applying, paint needs to be sanded to the bare metal. Make sure to sand outside of the repair area as Bondo will need to be spread and applied wider than the damaged area. (36-grit to 220-grit should do the trick for body filler application).

Does fiberglass stick to primer?

The answer is a yes! Fiberglass resin is a thermoset plastic and if the surface is properly primed, it will stick to it well.

What grit sandpaper should I use on Bondo?

If grinding is needed use a 3M™ 36 or 40 grinding disc followed by 3M™ 80 grit sandpaper if no grinding is required, sand the surface with 3M™ 80 grit sandpaper to remove all primer, paint and rust 1 to 2 inches beyond the outer edges of damaged area.

What grit should I use before primer?

When looking to sand a surface before applying primer, the best grit sandpaper to use is 320 to 400. Both these grits can effectively remove the existing primer and help you flatten the surface.

What is the best surface to mix Bondo on?

1. Mix on a Spreader Mixing Board designed for the job. Do not mix on cardboard, cardboard will absorb the important resins from the body filler and hardener. Lay down your filler and then apply the correct amount of hardener.

What will Bondo not stick to?

Clean and sand or scuff the surface to prepare it for body filler — it will not adhere to smooth, dirty or oily surfaces. Generally, if paint will stick, so will Bondo. 7. Conversely, if there's an area you don't want Bondo to stick to, apply a release agent (see tools and materials) or use Scotch tape or wax paper.

Can I use Bondo without hardener?

Without it the bondo won't get hard. Put a small piece of bondo on a board and run a line of hardener from end to end. It will take about five minutes to mix it up and apply it. If it starts tacking up, stop applying it or you'll mess it up.

How thick can Bondo be applied?

There is no minimum thickness for Bondo, but there is absolutely a maximum. You do not want to apply body filler to anything that is thicker than about a 1/4”. That does not mean it can't be done, but the repair will not last as long. Eventually the filler will shrink and possibly crack, or even pop off!

Can you Bondo over rusty metal primer?

NO, never. bondo goes over bare steel only. Never over any kind of paint, primer, etc.

When can you paint Bondo?

Bondo Fiberglass Resin is sandable in less than 2 hours, is compatible with all paints, and creates a strong and long-lasting bond.

Will primer fill 80 grit scratches?

High build primer will fill 80 grit scratches but it may take several coats. I usually final sand filler with 180 grit, after doing most of the sanding with 80 grit.