Hi all,
I can’t remember is it advisable to put filler on bare metal or use a prime first ?? I just want to make the door step look better after welding
Personally I would key prime and fill.
Primer then filler always for me like the added coat
Filler should always go on top of bare metal.
Filler should always go on top of bare metal.
This is correct!
For best adhesion, always put filler straight onto bare metal.
You will never feather the edges perfectly either with primer beneath
As the above, the filler needs to key so always on fresh clean metal
Filler should always go on top of bare metal.
Ok I have been doing it wrong.
What would the protection aspect of it be. I would of liked to have thought that by applying it to zinc primer would give it the protection from beneath.
midridge2 wrote:
Filler should always go on top of bare metal.
Ok I have been doing it wrong.
What would the protection aspect of it be. I would of liked to have thought that by applying it to zinc primer would give it the protection from beneath.
Providing you apply the filler to clean bare metal and it is mixed properly to the correct ratios then it won’t be a problem.
Remember, The correct use for filler is to even out lows and imperfections, if you are using buckets of the stuff then there is a problem elsewhere.
Once the filler is sanded, shaped and smoothed out, you can just go ahead and prime it as normal
MINIMADrt wrote:
Filler should always go on top of bare metal.
Ok I have been doing it wrong.
What would the protection aspect of it be. I would of liked to have thought that by applying it to zinc primer would give it the protection from beneath.
Providing you apply the filler to clean bare metal and it is mixed properly to the correct ratios then it won’t be a problem.
Remember, The correct use for filler is to even out lows and imperfections, if you are using buckets of the stuff then there is a problem elsewhere.
Once the filler is sanded, shaped and smoothed out, you can just go ahead and prime it as normal
Ok cheers. Learn something new each day.
Filling over epoxy is way I would go then seal top of filler with another coat after sanding
Epoxy primer may stick very well to bare metal but filler sticks best to bare metal and as Ben said its feathering the edges back.
I have never seen a bare metal panel go rusty when the filler has been ground out as it stops the Oxygen attacking the bare metal after the filler is applied.
I’ve just applied filler to a bare metal MGB bonnet this afternoon. Blocked it back and gave it a squirt of primer locally. It needs a couple of coats of High-Build ‘yellow’ primer, then a rub down, a witness coat and further rubbing down to get the profile correct. Then a final coat of white or grey standard primer and top coat.
Epoxy primer may stick very well to bare metal but filler sticks best to bare metal and as Ben said its feathering the edges back.
I have never seen a bare metal panel go rusty when the filler has been ground out as it stops the Oxygen attacking the bare metal after the filler is applied.
filler on bare metal will feather out nicely into the surrounding metal because the sanding process will not really remove any metal which is obviously all there will be beneath, where as if you have primer or old paint beneath the filler, when you rub it down you will be sanding the paint beneath too and this often leads to ‘mapping’ which presents itself as layers of rings around the repair.
More often than not, slight mapping will not really show to an untrained eye and it also depends on the top coat colour but it will be there and in extreme cases, you will see it in most lights.
I say use what method feels right for you but ultimately, applying filler onto the bare metal is the correct way and there is no risk of any rust or other problems forming beneath the filler providing you prepare your base properly and mix and apply your filler correctly.
If you are using an epoxy primer, check the manufacturer application directions. Some makes actually recommend that filler be applied over their epoxy primer - they feel their primer will grip bare metal better than filler, and in turn the filler will grip the primer better than bare metal.
