Is spray filler also an primer?

D

DiToni

Guest
Hello airbrush family

It's not yet a problem, just a question. I'm sprying a gastank on a bike. But for straitening i had to fill some holes and finaly i've sprayed an two components Universal spray filler with polyester base in it over the whole aeria. My question is: do i have to spray for the paint to stick a primer too?
 
Hello airbrush family

It's not yet a problem, just a question. I'm sprying a gastank on a bike. But for straitening i had to fill some holes and finaly i've sprayed an two components Universal spray filler with polyester base in it over the whole aeria. My question is: do i have to spray for the paint to stick a primer too?

With a polyester base in it, you shouldn't have problem since the base is more or less a primer, and the polyester will help with adhesion.

Having said that and depending on how well the base has covered, it would no no harm to apply a primer
 
thank you Madbrush, it's well covered so i think i take my changes and spray without the primer.
 
Just to chip in if it's not too late. I would think it should be fine, but depending on what colour basecoat you're going to spray, the right colour primer will help give a truer base colour, just a thought.
 
Thanks Squishy and Ultraz
The base coat is black metallic, de filler color is yellow. So a black primer could be a consideration. It's now the third time i have to spray it over again. The first time i've got blatters at some spots after i put the bike into the sun. So i thought i didn't wait long enough for the paint to the dry before varnishing with 2K. Then seccond time same problems again. so i sanded all the old paint of and yes there was the real problem, the old owner filled some holes without removing all the rost.

Now there is the primer question. Can i use any kind of primer without risking a chemical reaction between the metallic paint or 2K varnish?
 
Yes, any primer will do, just be sure to sand as much as you can and make sure there is no loose particles, you can do this by using a good de-greaser (ontvetter) and finish of with a tacky rag (kleeftdoek) afterwards.

All primers these days are more forgiving than the old cellulose stuff, they use different solvents and in some cases are even acrylic.
 
Wow thanks for your explanation madbrush and much more for your dutch translation. Your dutch language is way better then my scottish. ;)
 
DiToni, not sure where you are up to on your project as I am new to the forum, but this is an area that I have some experience. If you are starting from bare metal, the process should be - acid clean, etch primer, high build, sand, primer/surfacer, sand, colour, clear and if using an acrylic clear, sand again. If you are starting from a pre-painted surface with just a repair, you can start from the high build once prep sanded. If you are using 2k primer you must use 2k clear. If you are using acrylic primer then you have to use acrylic clear. The base colour is not as much of an issue, for example you could use all 2k products up to primer, Auto Air Colors, then 2k clear. If painting over an existing finish then you will need to use the same product types. If you don't know what the previous finish is then I would suggest going back to bare metal on the whole tank. If you mix 2k and acrylic in the prep and clear you will get a reaction in time. Each time you sand you should be using a guide coat. This can be either powder or a light mist of cheap black acrylic (not acrylic enamel). This is so that you can see where you have and have not sanded to achieve a smooth surface. The direction that you sand over a curved surface and the type of block you use will also have an effect on the overall shape of the surface. How course the paper is will depend on if you are sanding dry or wet but whatever product you are using should have a recommendation. The final sand before colour should be wet with either 600 or 800 but once again the product that you use will have a recommendation. Also you should be using a wax and grease remover and as squishy said a tack rag to achieve the best result. As for the colour of your primer, it should not matter with the black. This is only an issue with some colours that don't cover very well. Even then you wouldn't go back and change the colour of the primer, you adjust the first coat of base colour. The important things to remember are that the more time you spend on the prep, the better the end result. Also you need to adhere to the recommended time frames (at the rated temp) and allow each coat to flash (release the solvent) before recoating. Added to this, some products must be recoated within a specified time frame otherwise you will need to sand them back and reapply. This is due to the requirement for a chemical bond to the next step as apposed to a mechanical bond. I know this may seem like a lot but with automotive finishes it really is hours of prep for a couple of minutes of applying the colour. Hope this helps.
 
Thanks for the explaintion, smooftie. After 4 times repainting a petroltank from a motorbike i bought on the internet i finally found what was causing the problems. Everytime after spraying the clear, after a while it started to blatter on the place the original emblems where fitted. Rhe fourth time before clearing there was a tiny tiny spot wet. Turned out the tank had an initiny hole. So i went over to the original tank wich was in an awfull condition, sanded the whole thing bare naked, Primed the whole and filled the holes with 2k filler. Then sprayed the whole thing over with 2k spray filler. Sanded some more and washed the whole with wax and grease remover and with the tacky rag i wiped it. Then spraying the metalic black, sanding it with scotch brite, wiped it again with the tacky rag. Then airbrushing the whole with Golden, Schmincke and auto-air all acrilyc paint. Scotching the whole thing again removed the dust with tacky rag and started clearing with 2k. I'm not saying it's a 100% job, but i'm pretty pleased with the end result now. And even better the paint is staying on the wright place now. ;)IMG-20130726-00185.jpgIMG-20130726-00183.jpgIMG-20130726-00184.jpg
 
DiToni, from the pictures it looks great. The main point is that there is only one person that you have to make happy and that is you!
 
Thanks Smooftie, but i think your step by step will be very helpfull, the next time i do a project like this one. It's rather painfull to see your worked destroyed each time and not knowing what causes it.

Following your guidelines, will prevent problems and a LOT of frustration.
 
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