After sand blasting before priming

[White 99]

I have never done it before but I want to try to sand blast a motorcycle frame before having it painted. I am going to use fine coal slag in a HF sand blaster. I suppose after sand blasting I will blow the frame down with compressed air to remove the sand. What else is necessary to clean the metal before Etching Primer?
TIA.

 

[cvairwerks]

Wipe down with a good solvent to remove any oils or surface contaminants just prior to priming.

If you’ve never blasted thin tubing, be careful, work your way up on blasting pressure. Slag can be very aggressive, so take that into account and don’t stop the gun from moving while flowing abrasive.

 

[HMCFab9]

I have always used PPG DX330, but any brand of automotive grade wax & grease remover should be fine.

 

[sberry]

If you havnt removed wax and grease with blasting than wtf? Clean it first, blast, then scuff with maroon Scotchbrite, blow off and paint. The scuff does 2 things, it removes dust and blast material stuck on and smooths high sharp spots that poke thru primer. Wash hands well before you touch it and or wear some cotton gloves.
You can feel the difference after a light scuff. If one looks at magnified blasted surface can see how sharp it it. Some of the light primers fill in the pits but if a guy looks after can see little spikes right thru it. Don't put a bunch of stuff on and smear it around, absolutely no need.

 

[sberry]

So many problems where someone simply touched it. Main thing all the solvent and remover does is clean your hands. I see people walk up to cars all the time, run their hands on then, man that's smooth and can see rust spots starting later where a guy had his hand in a bag of chips before touching it.
When I first started painting I listened to all that ****, created another layer of work, stocked more **** and it never seemed to make a difference. Finally some eldtimer told me this, all that self etch, the wash wasn't helping.

 

[driz]

Save your cash and just buy the cheap hand auction one. In the end it’s faster and won’t continually plug and drive you crazy. The cheap one will last forever unlike the junk pressure pot with garbage valves and hose. I’ve had both. The big one will just take up room in your garage.


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[sberry]

I dont have a deadman on mine. All from scrap. Top valve is a Dord Radius arm grommet inverted, pull up to close and opens when pressure drops. Old ball valve on bottom for regulator. 3 ft wand.

 

[White 99]

Thanks for the ideas.
OP

 

[didit]

I agree with the wax and grease being removed before blasting. Why contaminate surfaces and media that will be reclaimed and used again? I run coarse scrub pads over the surfaces while watching for areas that need more paint or rust removal in the nooks and crannies or any sharp or deformed areas needing attention. By using the scrub pad over the entire piece you will be sure to notice any imperfections before paint. I normally blow off with dry air after, use prime wash if there is any residue after that, then a light wipe down with a tack rag. I usually use PPG epoxy primer, thinned with reducer and depending on the temperature, more or less of the required catalyst. For a better finish, even with just primer, especially on multi faceted surfaces, light multiple sprayed coats are better for getting all the surfaces covered evenly. Good luck!

 

[didit]

One other thought I would like to pass on that may be good to know. There is no better first step of prep used to promote good adhesion for any paint system than sand blasting. It provides the "tooth" for the primer. Products such as Metal Prep or self etching primers are not typically needed after blasting. I would suggest using the money saved by not using these products to upgrade to an epoxy primer that will provide better waterproofing protection. I know, I always have parts that have been blasted and primed sitting on the shelf waiting on paint. They are protected from any further oxidization because of the primer I use and can be safely stored before getting finish painted, without any fear of rust appearing.

 

[sberry]

Some of the epoxy like Corlar call for a rewet if it has been sitting a while.

 

[sberry]

I would suggest using the money saved by not using these products

In general I agree with that. Also its just more shat to smear around. They might have their place on existing paint but I never use it. Some care not to contaminate the fresh blast and a scuff to clean some sand is wayyyyy more important.
I wish I had an old pic file of some jobs I did to old equipment next to new. The customer was impressed with the speed of some new from another contractor,,, I went back a couple times and my old **** was wayyyyyyyyyyyyyyyy better than the new job simply cause I gave a **** and was a little careful.
Mine look good after 5 years and at 2 the new was blistering off. They know corporate memory is short, no one remembers who dun it or when. The contractor got it painted and paid.
I do cleaning prior to blast, the men wondering why I am ghoing and chip and scuff with the grinder and cleaning weld spatter if "we gonna blast it anyway"? First,,, blast is way faster and easier when its clean and not trying to get in cracks and corners and the paint isnt trying to cover protruding spatter. If anyone really had been watching my blast was actually faster, that and using the right sand.

 

[sberry]

Also,,,, I dont think a little rust hurts much as long as the etch is there, the primer simply seals it in. I painted a big truck equipment, looked terrible from water blast and surface rust, couldnt tell later. Looked at it down the road,,, wasnt much an issue.