epoxy primer question

[Mike(NEOhio)]

Planning to use it on the cast parts of my H after either wire-wheeling or sandblasting. I will not assemble it right away and likely to sit around for months. Epoxys have a recoat window. What would be the best way for painting later? Scotchbrite and paint? Normal primer coat over epoxy coat? I used a rattle can epoxy on an engine block and castings after they were hot-tanked and painted a year later. A friend who painter cars helped and he gave me some kind of solvent to wipe everything before paint and now I can scratch the paint with a fingernail.

 

[Welding man]

The epoxy primer I use has a 72 hour recoat window. It says if you don't you must sand and recoat with the same primer. I have always tried to topcoat within this window. Never took a chance on waiting longer.

 

[showcrop]

Planning to use it on the cast parts of my H after either wire-wheeling or sandblasting. I will not assemble it right away and likely to sit around for months. Epoxys have a recoat window. What would be the best way for painting later? Scotchbrite and paint? Normal primer coat over epoxy coat? I used a rattle can epoxy on an engine block and castings after they were hot-tanked and painted a year later. A friend who painter cars helped and he gave me some kind of solvent to wipe everything before paint and now I can scratch the paint with a fingernail.

Cast or sheet metal are done differently.

 

[Mike(NEOhio)]

The epoxy primer I use has a 72 hour recoat window. It says if you don't you must sand and recoat with the same primer. I have always tried to topcoat within this window. Never took a chance on waiting longer.

What brand is that? Only one I've used was in a two-part rattle can from S-W.

 

[Mike(NEOhio)]

Cast or sheet metal are done differently.

Concerned about castings at this point;

 

[Duner Wi]

Concerned about castings at this point;

Your best answer will be when we know exactly what product you are using. Honest.

 

[Mike(NEOhio)]

Your best answer will be when we know exactly what product you are using. Honest.

Don't have it yet. That's why I'm asking.

 

[Welding man]

What brand is that? Only one I've used was in a two-part rattle can from S-W.

I Use PPG Omni MP170. About $250.00 For a gallon for primer and 2 qts. activator. I use it on the whole tractor. Ornamental railings and gates that I fabricate and truck beds. Has worked very well on lots of applications.

 

[Stephen Newell]

Planning to use it on the cast parts of my H after either wire-wheeling or sandblasting. I will not assemble it right away and likely to sit around for months. Epoxys have a recoat window. What would be the best way for painting later? Scotchbrite and paint? Normal primer coat over epoxy coat? I used a rattle can epoxy on an engine block and castings after they were hot-tanked and painted a year later. A friend who painter cars helped and he gave me some kind of solvent to wipe everything before paint and now I can scratch the paint with a fingernail.

The recoat window varies by the individual product. All you would have to do is put a filler primer over the epoxy during the recoat window and you could paint it anytime. I would keep the parts covered in a clean place though. There is enough crud in the air to cause adhesion issues if stored for a long period of time.

 

[Dennis K (WA)]

I Use PPG Omni MP170. About $250.00 For a gallon for primer and 2 qts. activator. I use it on the whole tractor. Ornamental railings and gates that I fabricate and truck beds. Has worked very well on lots of applications.

I Use PPG Omni MP170. About $250.00 For a gallon for primer and 2 qts. activator. I use it on the whole tractor. Ornamental railings and gates that I fabricate and truck beds. Has worked very well on lots of applications.

My choice also.

 

[560Dennis]

What did Newbury Sandblast and painting use ?

 

[Mike(NEOhio)]

What did Newbury Sandblast and painting use ?

Don't know. They had a fire 4-5 years back and never reopened. And when I used them I only had the blasting done.

 

[kencombs]

I Use PPG Omni MP170. About $250.00 For a gallon for primer and 2 qts. activator. I use it on the whole tractor. Ornamental railings and gates that I fabricate and truck beds. Has worked very well on lots of applications.

PPG is good, but I've also had good results with cheaper brands. Like Kirker Enduroprime, which is my go to brand. Usually about $130 for a gallon of primer and a gallon of catalyst. Mixes 50/50 so you have at least 2 gallons sprayable, a little more if you add a touch of reducer. It can also be used as a sealer with a little extra reducer.

 

[tom upton]

Just my preference but I like to use transtar 2 part etching primer on casting. Save your Epoxy for the sheet metal.

 

[Mike(NEOhio)]

Just my preference but I like to use transtar 2 part etching primer on casting. Save your Epoxy for the sheet metal.

Interesting, everybody else here says epoxy for the castings.

 

[Stephen Newell]

Interesting, everybody else here says epoxy for the castings.

Epoxy will just bond better than anything else. Then if someday there is damage to the paint down to the metal the damage will stay there. With regular primer rust will bleed laterally from a damaged spot underneath the paint until one day you have a large chunk of paint fall off.

 

[kencombs]

Epoxy will just bond better than anything else. Then if someday there is damage to the paint down to the metal the damage will stay there. With regular primer rust will bleed laterally from a damaged spot underneath the paint until one day you have a large chunk of paint fall off.

As it was described to me years ago, epoxy sticks to everything and anything sticks to epoxy. And epoxy is not porous like most others so it makes an excellent barrier protecting from airborne water.

 

[tom upton]

Interesting, everybody else here says epoxy for the castings.

I have used both and find the 2 part etching primer is more forgiving of small amounts of crap left in/on the casting and just generally adheres to the cast better than epoxy. There is usually hard to get at spots that are never totally clean. I dont like to have the rearend/transmission of tractor blasted as worried about sand getting into bearings etc. If casting was sspc 10 near white perfectly blasted epoxy primer would be great, probably better than the etching primer. One tractor that I was being fairly fussy with I used etching primer on the bare castings, then put a coat of epoxy primer over that, but I think it was overkill as several years later I can not see the difference from casting done only with self etch then urethane paint directly over that. First 2 pics are my grandfathers 70 I used both on castings and sheet metal and third pic is 880 that just got etching primer on castings. Epoxy primer directly on bare sheet metal. The front pedestal on the 880 I ran out of etching primer so just put the epoxy on it alone. For some reason, maybe it got some oil on it?? a couple chunks of paint flaked off. I guess it boils down to what works for you, and I will continue to use etching primer on tractor castings as it works for me! One more comment about just priming and not topcoating within the recomended window- save yourself some work and possible grief by top coating now not later.

 

[woodman1928]

So first thing epoxy in a soray can inst a true epoxy its concidered a pre-cat primer like most other soray paints but it it is formualted close enough to a platisized epoxy to market it that. Honeslty crap stuff with false marketing.

I do a lone of cast stuff from the mechinery in my mill to tractors to engine blocks a decent epoxy is always the way to go.

Unless im doing a high end restoration theirs zero point to use an expensive epoxy primer. On almost everything i do thats for myself, or moderate end for sealing purposes on bear metal i use omni epoxy primer its good stuff but dosent have the solids count to thin it enough to glass a body job before paint. But we dont need that unless were building a $150k resto for auction.

Rember cast is rough and porous (all metal is unless burnished and polished to some degree. But cast is the worst.

Whenyou use a wire wheel you never clean the rust out of the lows in the sand casting and out of the porousness and eventualy it will contine under the primer.

I use a phosphoric acid wash on everything i do. For cast parts liek my tractor. I wire wheel just like you did. The i wash inlaqure thinner then i let dry then i flush the remaing dust out with alcohol in a water bottel with awhole poked kn the cap then i let dry…

Then spray with the phosphoric acid. For hat your doing you can just use metal etch from home depot will work good enough.

I let dry 24 hours then eiatber give it anouther wire wheel with a cup supper quick or hand scuff with 80 to knock some of the bloom off then wash with acetone to nutralize and prep.

The i can spray the epoxy

The thing with epoxys is you can alway recoat from anywere from 15 min to 48-72 hours after spraying without scuffing but if you go past that window youll have to scuff and unless you waite 5 weeks it will suck becose youll clog your paper up.

with the omni i recomend 2 medium coats 15 min betwen coats for your purposes its a tiney bit thinner than the epensize stuff and just a tad easier to run if you try and go one coat. Even doing to lighter coats the costs dont even come close.

I hope that helps

Im going to try to attach a picture of a wire wheed tractor casting and before and after pjosporc acid stching andy were you see balck was an area of rust i count see.

 

[woodman1928]

So first thing epoxy in a sray can isnt a true epoxy. its concidered a pre-cat primer like most other spray paints but it it is formualted close enough to an epoxy to market it as that. Honeslty crap stuff with false marketing. And alot of guys will talk about self etching primers these are primers with aphosporc acid in them and they were great in the days before Epoxys, these days they should just be left for lawn furniture you touch up every year. Youll seldom even see them in a quick fix colision auto shop anymore.never mind in a shop that does work that people care about.

I do a lot of cast stuff from the mechinery in my mill to tractors to engine blocks a decent epoxy is always the way to go.

Unless im doing a high end restoration theirs zero point to use an expensive epoxy primer. On almost everything i do thats for myself from cast to sheet, or moderate end for sealing purposes on bare metal i use omni epoxy primer its good stuff but dosent have the solids count to thin it enough to glass a body job before paint. But we dont need that unless were building a $150k resto for auction.

Remember cast is rough and porous (all metal is unless burnished and polished to some degree. But cast is the worst.

When you use a wire wheel you never clean the rust out of the lows in the sand casting and out of the porousness and eventualy it will continue under the primer.

I use a phosphoric acid wash on everything i do. For cast parts like my tractor. I wire wheel just like you did. The i wash in laqure thinner then i let dry then i flush the remaing dust out with alcohol in a water bottel with a hole poked in the cap then i let dry…

Then spray with the phosphoric acid. For what your doing you can just use metal etch / concreat from home depot will work good enough ( blue lable clear jug that looks green from the fluid)

I let dry 24 hours then eather give it anouther wire wheel with a cup supper quick or hand scuff with 80 to knock some of the bloom off then wash with acetone to nutralize and prep.

The i can spray the epoxy

The thing with epoxys is you can alway recoat from anywere from 15 min to 48-72 hours after spraying without scuffing but if you go past that window youll have to scuff and unless you waite 5 weeks it will suck becose youll clog your paper up.

with the omni i recomend 2 medium coats 15 min betwen coats for your purposes its a tiney bit thinner than the expensize stuff and just a tad easier to run if you try and go one coat. Even doing to lighter coats the costs dont even come close.

I hope that helps

Im going to try to attach a picture of a wire wheed tractor casting and before and after pjosporc acid stching andy were you see balck was an area of rust i count see.