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reducing 2K

6K views 11 replies 6 participants last post by  jcclark 
#1 ·
I am going to paint the hood on a 1968 Mustang for a fellow and he brought his own paint supplies. The primer is Mar-Hyde 2K urethane "ultimate" it seems to be a good primer with excellent build and it sands really good but it is thick as mud!, Even with my older DivillBiss with 1.8 tip it does not spray well at all and I was wondering what would happen if I thinned it beyond the 4-1 max recommended. Would this just reduce the build or would it be detrimental to the primer?
 
#3 ·
Red I used that primer for years as has Jim... I had to go to 2.0 tip to get it to atomize correctly... reduce it 5% and if that does not do it, go to 10% as crash has suggested... it will be fine, just build a tad less... a note for the use of that primer...make sure you sand down anywhere you are going to use it... it will fill most anything for now, but over time in the sun it will break down and if you have coarse sanding scratches like 80 grit, they will bleed through... trust me, I have had this happen with that exact primer years ago... I know they are not making it better than they did back then... used some of it last year before finding spi, and I liked it less than years prior
 
#4 ·
You can reduce it. They have two ratio's on the can, don't remember what they are offhand. The 4 to 1 is the primer to activator ratio. from there you can reduce it with a urethane grade reducer. But I don't see a problem going over a little, the coats will just be a little thinner. I suggest using slower reducer. Without reduction, it is almost like trying to spray bodyfiller, in fact thats what it looks like when it drys on the sides of the can. I've used this primer for years but now use the tintable version as it is a real light grey and can be tinted if you wish. The yellow just isn't too good for covering with most colors. I really like the primer though, I has as much or more build as the ppg k36, I think it sands easier, and the price is a heck of a lot better. Never had a problem with the primer and there are still a few cars floating around that I used it on. Its on my bonny and was put over bodyfiller finished only to 80 grit, followed by blocking with 180 and repriming. The car was done 5 years ago and no sandscratches are showing.
 
#5 ·
Usually have a 10% mark and a 20% on the mix cup.
I won't cut mine at all for initial priming and I use a 2.0 tip.
With the 1.8,which is "close" I'd do the 10% after catylizing and it ought to do fine and the build should be OK,Just don't bomb it on heavy trying to fill the well and let it flash off overnight after the 2nd coat.
Guide and block it with some 180 dry and hit it again same as before and you should have enough build to finish it out as long as the substrate was fairly "right". Guide,220 dry,guide,320 dry,grease & wax remover to SEE how the scratch looks and more wet if needed. Or a double gray scotch pad wet with some soapy water if it's close. I went to this gray pad wet lately and it's just a beautiful base to paint on. For what I'm worth.
 
#6 ·
Thanks, That answers a bunch of questions I had. The can gives 4-1 primer to activator with 1 part urethane reducer if needed.

BK, Very interesting note about the scratches since I did shoot over some small 80 grit areas and was impressed with the fill but I will sand that back out and redo it just to be safe.
 
#9 ·
Red I am not really sure why others dont have issue's with it and I have... I just know that when I changed my products, all those issues went away... since most of us bodymen/painters are concrete heads.. ( that is me for sure), I would rather use the more expensive primer and after my filler is sanded out correctly with 80 grit, move on to the next thing... Its cheap insurance IMO... I am going to try to move up to 180 if I can re teach myself.. now I will have to not get the filler worked all the way down before switching... but I began messing around with it last week... seemed to take more time than the old way, and I dont like that, but I will give it a try....
 
#10 ·
I probably wont buy any of this stuff I figure it is cheap for a reason. I do like the way it sands but that possible shrinkage problem is enough for me to avoid it, I realize that a topcoat can only be as good as what it is applied over. During what I like to call my "learning phase" over the last couple of years I used mostly the cheaper Nason paint but when I used the real DuPont on the last two jobs I did, one over-all and the front clip on my daughter's 04 Mustang, it was amazing how much difference it made. :)
 
#11 ·
I use the gray pads to finish off with. I get it right with the guide coat and check it with grease & wax remover to SEE if I've got anything way out that needs more work with paper and then I use the pad with the Ivory liquid soap or as Milo likes Ajax and "finish" the whole project.
Custom paint is just,another stage in the finish phase. We have to take it to the next level cause it's really put thru the N'th degree and scratchs are not well recieved.
It's overkill on repair work and I'm NOT saying collision work is sloppy but it's just that you don't have the time,or money for that fact,to dick around making it perfect. Repair work is an art to itself just like custom is and I would probbly suck at a repair shop cause I'd be spending way too much time on a job.
I had been using the scotch pads for scuffing but Bob turned me on to using them for finish sanding after a scratch issue I had and I just took it another step using them wet kinda by accident as I was using a red one to clean a panel after some blocking and was surprised at the finish left.
I still use Nason solid base but if it's a metallic or a special color,Chromabase is the choice. One thing with Chroma though,it is a different base and IF your sanding is not up to par,it will haunt you. Nason actually fills better,maybe cause of more coats,but I believe it's the enamel it's based on which does a better job of filling than Chromabase. I've learned to use Nason's reducers to MY advantage and I actually will use Basemaker instead for reducer if it's in the price range of the job.
 
#12 ·
I have used the MarHyde for 15 years now. I have never had scratches
come back to haunt me later. I did my own car about 4 yrs ago and it had
a lot of hail damage, no scratches so far.
The trick to not getting scratches is to let it cure before sanding.
I let it sit 24 hrs, wet sand it smooth then wait another 24 before painting.
I also over reduce so it sprays better, it also gets down in the scratches
better and does a better job when reduced a lot.
If someone is getting scratches they're usually rushing the job
and not allowing enough curing time. :pimp:
 
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