Is soda the best for blasting sheet metal? Whats best aggregate for blasting the frame? Should it all be primed first right out of the blaster? I realize these could be elementary questions, however I imagine there will be some interesting opinions on this.
Well~ I would prime it ASAP. Just because I will never be more pristine than at that moment. But of course, that's an opinion of an absolute novice!
We use several different approaches depending on the design of the vehicle and extent of the corrosion. On a 56 Ford Victoria that had many blind areas and pervasive rust in these blind areas we had it chemically dipped which gets every last bit of rust no matter where it's at but cost $2600 (ouch). This also removes all the factory seam sealer and it's hard to replace in the blind areas. We have a soda blaster and use it on fiberglass, aluminum, and where the glass or trim is left in place since it doesn't harm them. We also have glass beads, plastic media, walnut shells, aluminum oxide, and maybe a couple others that are better for your health but nearly always end up using the old stand by--blasting sand. It CAN be a hazzard but if used with precautions it doesn't have to be dangerous. A respirator, fresh air supply helmut, and working outside when there is a good breeze disperses the dust quickly. Our shop is in a rural county but just 2 miles away and across the county line doing this is a no-no so check any ordinances that may apply. On frames we use #4 blasting sand to remove all the crud and rust then follow this with sugar sand to give a glass beaded type surface that takes primer well and doesn't need sanding to give a gloss if that is desired. We use epoxy primer, usually PPG's DP 40, immediately after blasting even if filler work is to follow. The filler adheres to the epoxy just fine and no rust is allowed to form. After blasting you can also use POR 15 or Eastwoods frame painting kit if you desire. On sheet metal we use sugar sand and just two of the guys are allowed to do the blasting since real damage can be done by inexperienced hands. Again epoxy is applied immediately after blasting. If more than 24 hours passes before top coating, it always does, remember to scuff the primer to get good top coat adhesion. Metal work can be done and filler can be used with the epoxy in place. Pics of Model A frame and 56 frame using this method.
sealer Evan Is it important ot get more than just a primer on the "naked" steel so that rust does not take holdI have alway had this thought in the back of my head because im only 20 minutes away from the Atlantic and some nights you can smell the sea air. I just dont know how soon rust will start and think it a shame to do all the work of cleaning a frame or whatever and putting a primer on it that does not seal out the enviroment? Im not familiar with the PPG primer you mentioned does it seal also? Bill
Flash Rusting Bill ; It starts almost immediately , follow Even's good advice and primer the bare metal as soon as you've got it blasted and dusted off.... BTW : I've had FOUR Model 'A's and NONE had a frame that looked like that !
good advice Nate I follow everyones good advice and so far its been working for me Im just thinking there isa difference between primer which is for lack of a better word "poreous" and sealer which will keep out the elements. Now im pretty sure the paint on those Model A frames will keep out the elements just wondering how quicklythat was put on. I also thought that if there is work goign to be done on the frame it would be best to have it sealed with soething more substantial then primer. All of my thoughts are moot if the primer Evan uses is considered a sealer also which may be the reason he uses that particular primer Bill
Modern Primers You're right on track Bill ; Modern primers are sealers , follow Even's guieds closely and you'll be VERY happy with the results . if you need old timey farm repair help , ask me .
Soda blasting leaves a thin film on the metal that will hold off rust for a short time. On bare metal, use an etching primer if possible. A standard primer is very porus, and should be only temporary before paint or further work. If allowed to sit in the weather, primer will eventually let rust form.
Bill, since your in extreme conditions so near the ocean your best bet is POR 15. It is impervious to rust and has proven itself for the last 20 years or so. It's one drawback was no topcoats would adhere well but they now offer topcoats that work. Without a topcoat it does not resist ultra violet rays but this isn't a problem on frames,floor panels, and other places not in direct sun light.
thanks Evan I was under the impressoin that POR 15 could also be appplied directly over rust am I mistaken I expect to clean to bare metal as best i could if not soda or bead blast then apply what ever sealant i choose
What Luck! OK, Neil. (You may want to have a seat for what I'm about to tell you...) I like the patina look too! My only problem with the patina thing is I can still hear the rust growing as bad as you can hear fingernails scraping across a blackboard!
Yes, it is formulated to be used on rusty surfaces but not loose scale or any contaminents. This works in ones favor in not having to blast/clean to bare gray metal but rather just de-scaling and cleaning off oil, grease, etc., and then painting. The kit comes with a cleaner, metal prep, and instructions.
Applying POR 15 What is the recommended method for applying POR 15? I don't think my compressor is big enough to push a paint gun. What kind of finish would I get with a good brush?
Brushwork With POR-15 If you've scrubbed all the rust off and de-greased the metal , it'll actually flow out pretty well and leave NO brush marks . BTW : they've improved it so no longer fades in direct sunlight . I know many who use it for all the under hood engine bits and chassis black too .
