Bilt Hamber Highbild Filler Primer is a high build, easy-flatting filler primer in an aerosol can. You use it to level out small imperfections, sanding scratches before you spray the topcoat. Once flatted, you are left with an even surface. This guide shows how to apply Bilt Hamber Highbild as a high build primer, how long to wait and which grit to flat it with.
We use this filler primer for repair and restoration work, on bare metal, on GRP (fibreglass) and on fully cured paint. The key facts come first, then the steps.
Key facts about Bilt Hamber Highbild
Item | Details |
|---|---|
Type | High build, easy-flatting filler primer in an aerosol can |
Suitable for | Bare metal, GRP (fibreglass), fully cured paint |
Shake before use | 2 minutes |
Spray distance | About 25 cm |
Dry film thickness | Typically 25 to 50 microns |
Scuffing existing paint first | Grit 280 to 400 |
Flatting Highbild itself | Dry grit 400 to 600, wet grit 600 to 800 |
Drying times (guide) | Touch dry 30 minutes, flat after 60, overcoat after 90 |
How to use the filler primer from the can
Prepare the surface. Key existing paint with grit 280 to 400 for good adhesion. Degrease bare steel thoroughly with a solvent. If you are unsure, test a small area first to see that the primer bonds to your paint.
Mask up and pick your spot. Work in a dry, well-ventilated space, out of direct sun and at a moderate temperature. Mask everything that must stay clean, including the edge of the repair.
Shake the can. Shake for at least 2 minutes, and again after any break. Then spray a test patch on cardboard to see the pattern. The valve has an adjustable fan, so set the width to match the size of your repair.
Spray thin, even coats. Hold the can about 25 cm away and move in straight passes with overlap. Build up with several thin coats rather than one wet one. That avoids runs and keeps drying time short.
Let the primer dry. As a guide, Highbild is touch dry after about 30 minutes, ready to flat after 60 and ready to overcoat after 90. Temperature, airflow and film thickness all play a part. An infrared lamp can speed up drying.
Flat it level. Use dry grit 400 to 600 or wet grit 600 to 800, preferably on a sanding block so flat areas end up truly flat. A light mist of contrast colour as a guide coat shows low spots straight away. If a low spot remains, spray another thin coat and flat again.
Clean and topcoat. Blow off the dust, degrease once more and spray your topcoat. Highbild is designed to be overcoated with a wide range of single and two-pack finishes.
Which abrasives suit Highbild
For machine sanding on a 150 mm sander with extraction, take the Mirka Abranet Ace Sanding Net 150mm P400. It sits inside the dry range of grit 400 to 600. For edges, profiles and wet hand sanding, the Mirka Abralon Sanding Pad P500 is handy, because the pad is flexible and works wet or dry. For more on sanding with an orbital machine, read our guide to the Mirka Deros 650CV sander.
Common mistakes and tips
Spraying coats that are too thick. Build up with thin coats and give each one a moment.
Not shaking enough. Two minutes of shaking prevents an uneven spray and an uneven film.
Flatting too early. Wait at least 60 minutes, longer in the cold. Primer that is still soft clogs your sandpaper.
Using too coarse a grit. Stay with grit 400 to 600 dry or 600 to 800 wet, or the sanding scratches will show through your topcoat.
Skipping the prep. A degreased, keyed surface decides whether the primer stays put. For degreasing paint just before spraying, see our guide to the Koch Chemie PPS Panel Preparation Spray.
Starting without a test patch. Spray a bit on cardboard and test on a small area of paint before you tackle the whole panel.
What to combine with Highbild
On bare steel you normally work in several layers. Bilt Hamber etchweld bonds chemically to bare metal and, according to the maker, forms a base for further paint build with a filler primer. For bare steel and welds that need extra protection there is the Bilt Hamber Electrox Zinc Primer. How to use it is covered in our guide to Electrox zinc primer. If there is still rust on the metal, work through our guide to removing rust from your car first. More abrasives and primers are in the sanding and paint preparation and spray can and primer categories.