DPLF Epoxy Primer questions

[uk_figs]

Seems to be two approaches to scuffing the aluminum prior to applying DPLF, most say use red scotchbrite pad but some say use 80 - 150 grit which is what the data sheet says. I tried both on the underside and the grit really scratches up the surface and I am concerned the scratch marks will show through. Will the bond be good with the scotchbrite method.

Second question is the time available to spray the topcoat (DCC Concept single stage), data sheet says from 90 minutes (2 DPLF coats) to 7 days, some people say wait 2 days for some curing and others say 7 days is the absolute outside before you have to scuff and reshoot another DPLF coat. Would appreciate some feedback from successful PPG users.

 

[D-Dubya]

Data Sheets

You can download the technical data sheets from the PPG web site, or get them from your friendly local distributor. They'll tell you everything you need to know in a relatively simple format. And while I don't remember all the topcoat and drying times, I think they say maroon Scotchbrite pads are all you need to give the primer something to hold on. But the sheet will tell you for sure.

 

[DanH]

Seems to be two approaches to scuffing the aluminum prior to applying DPLF, most say use red scotchbrite pad but some say use 80 - 150 grit which is what the data sheet says. I tried both on the underside and the grit really scratches up the surface and I am concerned the scratch marks will show through. Will the bond be good with the scotchbrite method.

80-150 sounds pretty rough for aluminum. I've tried 220, 400, or scotchbrite on different aluminum parts and can't see any scratching. Bonding to aluminum seems to be a matter far beyond mere choice of grit.

I sprayed DCC directly over DPLF after 220 sanding on glass and didn't see any scratching. You could probably use the very coarse grits if you plan to apply K36 or another high-build primer/surfacer over the DPLF.

Second question is the time available to spray the topcoat (DCC Concept single stage), data sheet says from 90 minutes (2 DPLF coats) to 7 days.

Translation: shoot anytime after the majority of the solvent evaporates (flash time), but before the epoxy components fully cure.

Only used a quart of DCC, but don't recall waiting very long.

Regarding K36 over DPLF, I cornered a experienced PPG factory rep in the paint store one day and his advice for maximum DPLF-to-K36 adhesion was to "shoot as soon as you can clean and reload the gun".

 

[broken1234]

Sooner is better with DPLF, but the tech sheet says up to 7 days.

Red scotchbrite is considered to be 400 grit. Gray scotchbrite is 600...

Brad

 

[uk_figs]

Thanks

Appreciate the feedback and clarification, will go with the red scotchbrite

 

[Guy Prevost]

I think red scotchbrite would be fine. I used 220 grit on a random orbit sander and had no visible scratches. I used DX1791 under the DPLF though. As others have said, my data sheets say 7 days is the outside for topcoating with DCC Concept.

 

[dedgemon]

red sctchbrite

or even gray is fine. Just get it really cleam afterwards. Shoot the topcoat after it flashes (20 minutes or so).

DPLF is great stuff. I've never seen an adhesion issue with well scuffed aluominum.