Block sanding question

[1BAD68]

Just got back from the paint store.
The owner strongly recommended against using the poly primer's, he said if there is any adhesion problems it will be a nightmare down the road (cracks, chips, etc)
Instead he recommends "SEM Metalock DTM high build primer"
He said it goes right over all your filler, glaze and bare metal because it's epoxy so it seals and has "superior" adhesion.
It's more expensive than the Evercoat but it eliminates the self-etch step so it comes out about the same cost.

Anyone ever use this stuff? Good, bad?

[73rallye440magnum]

Adhesion issues? Don't drink that Kool-aid.

If your surface is well prepared you will not have any adhesion issues using spray poly.

Spray poly is an excellent all around product. Minimal shrinking, and really "seals" everything beneath it well.

What credentials does the owner have?

Other than filling pinholes, try to stay away from glaze. It shrinks a lot.

[jaak]

He's blowing smoke, just trying to sell you something else. Heck most guys at local paint stores around here don't know much about painting....they are salesmen for their products. Polyprimers have been around for years, and millions have used it. Ignore that guy and order it online.

And it Im not mistaken (I would have to look up/read the tech sheets to be sure) the only difference between Evercoats featherfill and slicksand is, they claim slicksand to be a DTM primer....but I would still use epoxy on bare metal,

Jason

[Charger-Bodie]

Poly surfacer is one of the best things to happen to the resto business in years. High build ,no shrink. Its win win. Most poly surfacers don't like self etch though unless they are the newer low to no acid and phosphate free. If you do use etch make sure you let it dry 100% thoroughly before spraying poly surfacer. But by all means use the poly. It save the block and prime 5-6 times that some do because regular surfacers  cant be sprayed safely to the kind of mil build that the poly surfacer can.

[elitecustombody]

should,would or could,

But I don't recomend applying bondo=filler over bare steel. If you ever had to remove someone's old body work that was done years ago, you would know why.

Do all your straightening,welding,blast ,epoxy primer and then filler,then high-build primer.

[73rallye440magnum]

^ X2. Yep... put your filler over a scuffed epoxy.

[Indygenerallee]

x3 filler over epoxy

[AmadeusCharger500]

Could we get a x4 on that?

Seriously I am scratching my head with the things I've heard previously on other posts.

[superbirdtom]

A lot of good info and bad info on here. . I take it you are going to prime and block out the charger in the photo. . If you are . then seal it with ppg dp- 50 epoxy primer then use what ever brand of poly primer.    I used feather fill . Amak . back in 1978.  I just used some upol poly primer.    All of them are basically the same  very high build.    your question was about blocking.    after applying  a gallon of featherfill or whatever.  Then guidecoat the body  with a rattlecan of black lacquer primer.   this is like dust and won't clog your paper.  immediatly start taping  main side lines off.   start on top of lines .  then you move tape to bottom of line.

                               use a long board first.  I use a pneumatic hutchins  jitterboard before all the hand bocking. and get 90% done by machine.  When you block go diagonally then switch to opposite.  then go straight up and down.  this croshatching is the best method.  keep block firmly flat.  If the guidecoat reveals any low spots  or high spots .  stop!  and work on another area.   you can come back to the low and high spots later and fix  them .   no one can possibly write all the blocking techniques here its complicated.  But never reprime poly primer without sealing spots first.   and never paint directly over poly primer  always use sealer over it.     and man it stinks  because it is fiberglass.  use a mask!  and ventillation.  good luck.

[1BAD68]

Ok let me get this straight.

First step, epoxy primer.
Second step, all your filler and repairs.
Third step, poly primer or whatever you use followed by blocking.
Fourth step, epoxy primer to seal everything before color.

I didn't take the entire body down to bare metal, so is the epoxy in the first step good to go over bare metal, filler, old paint, etc? (see photo)

[superbirdtom]

Yes  First wipe it all down with some mild wax and grease remover. this picks up the sand dust and grease fingerprints etc.  then just epoxy seal right over your car as its sitting there.  you can let that epoxy sit for a day. then coat entire car with a gallon of slick sand- amak -featherfill- or what ever poly primer you want to use.  it is very thick so you must have a gun that will shoot it.  . some parts of the car look like they might only need a little poly primer the bondoed areas and sides need very thick heavy coats.

                    The poly primer sets up fast so as soon as it turns flat your ready for your next coat.  Then let it sit for however long you want to gas off.  Id let it sit for at least a week before blocking. all depends on temp. and where you live. I did a 66 mustang fastback 4 years ago and used my 2 qt pressure pot setup. it worked great  no overspray ,no waste.  but most of the primer will go onto the car as it goes on thick and not well atomized. god luk.

[bill440rt]

I agree with the techniques posted, however I NEVER use a machine to try and get panels straight. I ALWAYS block with a longboard by hand.
Doesn't mean one is right over the other, just a preference.

[superbirdtom]

If you get a hutchins oscilating long board and use it for 15 years like i have it becomes an extention of your body. I always end up doing my final 8% blocking by hand . It also depends on the car . if its  round I use grill brick to get the shape. I have so many hand blocks and ones ive made myself out of hard foam just for a certain car.  If you had to do as much body work as I do and are on comission . you find out the fastest way to get the job done. -- the guys in the shop that do all this hand blocking are as slow as molasses and their paycheck shows it. I am way faster because of my techniques . and my work is very straight. . my rule is why torture yourself and your body with all the hand blocking when I get the same results in a tenth of the time.

[bill440rt]

Doesn't mean one is right over the other, just a preference.

Ask 20 bodymen about technique, and you'll get 20 different answers. Again, doesn't mean one is right over the other, just a preference. Bodywork is somewhat of an art form, and each artist has their own style.
Whatever works for you, bro. 

[superbirdtom]

It depends on what the definition of body man is . and where they work and how many years they have been doing bodywork. for example. If you work now like i do in a comission body shop where the estimats on the job says 10 hours to fix a dent. and you can do it in 2 hours. ,you still get paid for 10 hours. the goal of comission bodyman painters is to get in as many hours as possible in a two week pay period. I usualy beat the pants off the estimates. I can get 100 to 150 hours in a two week period. at a base pay of 27 dollars per hour  .  I watch a kid right out of body school, been with us for 2 years smoke the veteran of 12 years on hours. why? because i took him under my wing as he showed an apptitude twards the trade. and promosed he would listen to me and not waste my time.  as he gets faster he feeds me more work to paint. the other guy, never listened to me a know it all. and is slow as a turtle. thus the older guy although has 5 times the experience earns less.   now why is this . It is because he hand blocks too much.
                    Ask 20( journeymen) 20+ years bodymen and if theyre any good and earn a lot theyll all tell you do 90% of your bondo work by machine and do the final 150 grit with hand blocks before it goes to the paint dept. to get primed and blocked and painted.  Ive also worked in some great street rod shops. thats a whole diferent world. But it still holds that when a machine is faster to get close  you use them . sometimes its only 60% machine and 40% hand blocks. but using a hand blocking technique from when you skim the whole car like a lead sled.  youd be nuts not to use a machine.  
                    Ive been through it all watching blood drip from my fingertips. Ive also restored a lot of mopars. the challenger is the easiest one in my opinion. Lots of machine blocking there. .  The kid at the shop now makes 2 grand more per month than the hand blocker and he still can't figure it out .  I gave up on him quite a while ago.   believe me with hand blocking you get an artists feel like the guys did who chizzeled the car out of clay . theirs lots of motions you make in an 8 hour day at a shop, and ive got it down to maximize all my motions to make more money . thats whats it all about.             I wish i could fly down and block out that chargers prime job.  Ill take my machines and have it 90% blocked in a day.                don't get me wrong  hand blocking is still alive and I do it too but only 10%.  another guy at another shop quit and went to work for us. now  Im not going to tell a 20 year guy what to do. But I could not believe my eyes at his horrible techniques. well he lasted 3 months and quit because he was so mad at how much work i churned out and my paychecks. theirs guys out there that have been at this trade for 30 years and still do slow bad work.                      

[bill440rt]

Right.
Very familiar with the workings of a production shop & techniques. I have plenty of air sanders, longboards, DA's etc that I will ever need, all have seen many hours. If I was doing a job in a production shop on a commission pay scale then absolutely my air tools would be the first thing I grab & send the job on down the line.

But this is getting completely off-topic from the original intent with the OP's question.

1BAD68, sounds like you've got a good grasp on the project at hand, & looks like you've done plenty of blocking. Use the poly and have at it with whatever techniques work best for you. There's some great info/tips in this thread.

[NHCharger]

I'm in the same boat as 1BAD. I'm almost ready epoxy prime the back half of my Charger. I've been searching through other thread about this plus starting my own. Been writing down all this different info. My head is spinning but I'm going to follow the same steps as 1Bad. Additional questions. How many coats. I've read 3 coats of epoxy and 3 coats of poly primer. The back of the Charger is bare metal. sanded with 80 grit. Should I sand with 180 before i epoxy??

[AmadeusCharger500]

I'm ordin some of this stuff recommended on this post, My local shop says they can get the Feather fill but when I told them I wanted to epoxy primer the whole car they said way too expensive then recommended a product called direct to metal. They said it would seal up the bare metal as well as sanded/oldpaint.

[1BAD68]

Was it Metalock? That's what my paint store recommended.

[Silver R/T]

You don't use epoxy over self etching primer. Use good epoxy ie SPI, and it's cheaper than PPG

[superbirdtom]

I wish i could use spi or standox. but Im stuck with ppg for the most part.  I hate ppg pricing, its just no worth the price,  and i noticed that the dbc basecoat that we switched to , dosen't go near as far as the old dbu system.  manufactuerers like ppg are thining everything out, and scrimping out on  material coverage.  The old  scarlet red 654 goes twice as far as the new 1677 dbc scarlet bright red toner. its amazing, and every year they go up like clockwork.  thats why everyone is trying so many different products.  gets aggrivating for all.     

[elitecustombody]

I'm in the same boat as 1BAD. I'm almost ready epoxy prime the back half of my Charger. I've been searching through other thread about this plus starting my own. Been writing down all this different info. My head is spinning but I'm going to follow the same steps as 1Bad. Additional questions. How many coats. I've read 3 coats of epoxy and 3 coats of poly primer. The back of the Charger is bare metal. sanded with 80 grit. Should I sand with 180 before i epoxy??

IMO 180 is too fine, leave 80 grit scratches on bare steel,that way you get even better mechanical adhesion combined with chemical adhesion that epoxy provides for best results 

[bill440rt]

I'm in the same boat as 1BAD. I'm almost ready epoxy prime the back half of my Charger. I've been searching through other thread about this plus starting my own. Been writing down all this different info. My head is spinning but I'm going to follow the same steps as 1Bad. Additional questions. How many coats. I've read 3 coats of epoxy and 3 coats of poly primer. The back of the Charger is bare metal. sanded with 80 grit. Should I sand with 180 before i epoxy??

IMO 180 is too fine, leave 80 grit scratches on bare steel,that way you get even better mechanical adhesion combined with chemical adhesion that epoxy provides for best results 

I agree.
Similarly, if you're going to do bodywork over the epoxy hit it with some 80-grit on a DA first & then do your bodywork over that.
If you are planning on putting hi-build over the epoxy (or poly surfacer, etc), then 2 medium coats of epoxy should be fine.

[AmadeusCharger500]

They just called it DTM or direct to metal. I'm going to pick it up today.

[elitecustombody]

I would stay away from DTM 2K primer .If you plan to shoot bare steel,invest in epoxy primer. You will thank me later. According to label Evercoat Featherfill supposedly has great adhesion on bare metal,but you think I would want to take that risk on customer's car? Not a chance! Want to know why? Because it does not offer good adhesion on bare metal.

Bottom line is,if you want ultimate adhesion and moisture barrier,use EPOXY primer! No  DTM 2k can offer that,plain and simple.

If you are on a budget, look into Sherwin Williams DP800 epoxy primer. It's awesome stuff and cost around $120-150 per kit gallon of primer and quart of catalyst,I use it all the time.