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Need three questions answered please!

2K views 9 replies 4 participants last post by  milo 
#1 ·
bare with me on some of these still learning here! :D

1- Understanding that BC is not to be sanded before CC'ing..... I was just curious if you need to sand a spot or two due to a run or dirt nib, etc... do you guys usually reshoot BC in just that spot or the entire panel again?

2- Im trying to make some final decisions in how Ill be organizing my garage spray booth, does the vapor stay low to the ground or go skyward?
I ask cuz I only have ONE window in there and I was hoping t use that as my exhaust.

3- When painting a car with plastic bumpers, do you remove them from the car or leave them on? Looking at my car it just looks like its gonna be a PITA to sand the seam but that may be the fun part of prep, right?

TIA!
 
#2 · (Edited)
First off, please, read the tech sheets on the products you are using. The manufacture spent hundreds of thousands, possibly millions of dollars developing the products, they REALLY want them to work well for you. They lay it all out in the tech sheets, from start to finish what you need to do to make that product perform at it's highest level.

Reading tech sheets can be a little confusing if you are not use to them. And they will leave out some little things like your question number 1. Most tech sheets will say something like "Lightly sand dirt nibs and recoat prior to clearing" and that will be it. Some like Sikkens "Autobase" tech sheet has a full explanation of these repairs covering a few pages of the tech sheets!

1. Basically, you treat it like you were "spot repairing" a previous paint job. You lightly sand this area after the base has flashed well and is good and dry to the touch. You have to take great care in not damaging the base with the edge of the paper and use VERY clean water and paper. Most bases are kinda delicate without the clear to protect them. After sanding, you can, if that is the only place you need to paint, just "spot paint" the area blending out onto the surrounding area. Then clear the whole thing after that last application has flashed properly.
READ THE TECH SHEETS! There may be a recoat window you have to adhere to after you spray the base that may be an issue.

2. The vapor will go EVERYWHERE. I mean EVERYWHERE we are talking in your cupboards, everywhere. There are two big issues, real big issues with home spray booths. First off, if the fan doesn't evacuate the overspray it will fall back onto the car and effect the gloss and texture of the clear. If you are going to sand and buff the whole thing, it isn't that big of a deal, but depending how much overspray and how fast the clear flashes that is on the car it can be kind of a mess. Secondly and MUCH more important is your health. If those fumes/vapors don't get out, the concentration of nasties (like Isocyanates) can get VERY high in there make it a VERY dangerous environment.
What protection do you have?

3. You remove the bumpers if you want to do a nice job. What kind of car are we talking about. Most late model cars bumpers come off SOOOOOOO easy I wouldn't even think of leaving them on.

I want to beat a dead horse with this reading the tech sheets thing. It is not only that, the tech sheet has a phone number where you can call, usually toll free, and talk to the tech at the manufacture. It is best to get the right information about any specific issues concerning your paint.

Many of these products from one manufacture to the next are pretty similar technologies. However, there are little details that could make a big difference. For instance, the recoat window with base coats go anywhere from 24 hours to 7 days! Depending on the brand. Recoat on etch primer, anywhere from 24 hours down to 4! Again depending on brand or part number.

If the "R&D" department found that by you wearing a clown suit while painting produced a better job, that would be in the tech sheets. In other words, they REALLY want their product to work, they have it all layed out in the tech sheets.
 
#3 ·
sportbikeluvr said:
bare with me on some of these still learning here! :D

1- Understanding that BC is not to be sanded before CC'ing..... I was just curious if you need to sand a spot or two due to a run or dirt nib, etc... do you guys usually reshoot BC in just that spot or the entire panel again?

You can usally blend/fog on a little color to cover those tiny scratches in just the area of the problem,

Here's one, , If you find yourself wanting to wet sand a little problem...use a little Windex instead of water with your sandpaper...you'll see
 
#4 ·
Re: Re: Need three questions answered please!

Here's one, , If you find yourself wanting to wet sand a little problem...use a little Windex instead of water with your sandpaper...you'll see [/B][/QUOTE]
*************************************************88
Did not know that, will try.
Another thing that works good if your wet sanding in a rush, Is wet the paper with wax and grease remover, it will normally let you get on it in about half the time as with water. What i mean if the base needs to set 20 minutes to sand with water you can use the wax and grease remover in about 10 minutes --(not waterborne type)
BUT, only wet the paper and not the car, you puddle it you could be in trouble.
Not for the faint hearted for sure.
Of all things learned this from a ppg rep about 12 years ago.
 
#5 ·
Many thnx gentlemen!

MartinSr: I appreciate the heads up on Tech sheets, thats actually the first thing I usually do (dl them off their site) when decide on a specific product. I was just a lil confused on spot sanding repairs before moving onto CC. thnx!

I planned on using a tightly sealed plastic tent in the garage with a filter covered fan in the window. Unfortunately this isnt somethng I gave much thought when I decided that I wanted to learn to paint my MC race skins myself sooooooo needless to say Im about 2 months past overdue on getting that project started and finished. :(

also for now I only have a $40 respirator......I may look into one of those homemade fresh air units but realistically Im looking at doing 1-2 projects a yr if that so I was kinda thinking about just goin with the respirator. :pain:
 
#6 ·
If you plan on shooting a couple of cars a year, do yourself a favor and BUY a fresh air set up, leave the home made idea to patio tables and basket ball back boards. Buy a quality factory tested fresh air unit. Autobodystore.com has a "Hobbyair" system for about $400.00.

Barry, I am sure you have found what "wax and grease remover" to use and how to be careful with it while sanding basecoats. But honestly, for a newbe, I think he should stick to water. There are a number of different wax and grease removers all the way from mild (mostly straight mineral spirits) up to some pretty agressive solvents that will attack an uncured (or for that matter if the base doesn't use a hardener it never cures, only "drys") base coat. Plus you run into the chance (opening a whole new window of failure) trapping solvents from the wax and grease remover in the base.
Grabbing the wrong wax and grease remover and then applying more base or clear over it before the solvents have completely flashed out could end up biting you in the butt.

Milo, Windex, again, stick to the tech sheets. Windex has dyes, ammonia, these are things you don't want to mix with your paint system. :welcome:
 
#7 · (Edited)
sportbikeluvr said:
[
2- Im trying to make some final decisions in how Ill be organizing my garage spray booth, does the vapor stay low to the ground or go skyward?
I ask cuz I only have ONE window in there and I was hoping t use that as my exhaust.
I would use that window for exhausting . You'll need a way for new air to get in. A screendoor frame with a couple ac filters taped in it and fitted to the door way will help clean new air but for the most part you'll only turn the fan on between coats and after clear. If you don't move the air around so much it won't put dirt in your paint. Wet the place with water just before paint you'll be ok.
 
#8 ·
Barry, I am sure you have found what "wax and grease remover" to use and how to be careful with it while sanding basecoats. But honestly, for a newbe, I think he should stick to water. There are a number of different wax and grease removers all the way from mild (mostly straight mineral spirits) up to some pretty agressive solvents that will attack an uncured (or for that matter if the base doesn't use a hardener it never cures, only "drys") base coat. Plus you run into the chance (opening a whole new window of failure) trapping solvents from the wax and grease remover in the base.
Grabbing the wrong wax and grease remover and then applying more base or clear over it before the solvents have completely flashed out could end up biting you in the butt.

Milo, Windex, again, stick to the tech sheets. Windex has dyes, ammonia, these are things you don't want to mix with your paint system. :welcome: [/B][/QUOTE]

++++++++++++++++++++++++++++++++++++++++++++++++
Like I said, NOT for the faint hearted! Oh and your right you do this with ppg440 and it would wash it right off.
Since I learned this can't tell you how many painters have showed it to and gotten out of a jamb in a hurry. and since most
painter have laying around something close to 900 or 330 its not an issue as they are smart enough to know mild from killer.

RE: Windex, That kind of intrigued me so bought some and broke it down today.
Really, there is nothing in there that would hurt paint in any way
and ammonia is one of the best cleaners out there but you want the non-streaking and that what showed up in the windex.
Dyes and deodorizer's (also found in the windex) have no affect on paint as a matter of fact you can blend them in most paints, well you can't but the factory can.
 
#9 · (Edited)
Honestly Barry, I have worked with hundreds of painters, most do not know know there are different "strengths" of wax and grease removers, honestly! Or if they do know, they really aren't as keen as you are.

On this and the Windex, I am not saying they are that bad of an idea. What I am saying is, MOST people who work with this stuff, pros and home hobbyests alike, are not going to study something to the degree you are talking about. They are going to hear, "take some wax and grease remover or window cleaner and have at it". EVERY manufacture makes products and recommendations that cover every single circumstance. If the average home hobbyest takes advantage of the time and money the manufacture has spent on developing the products and follows there lead, they will be better off.

This is it in a nutshell, follow the tech sheets, follow what the manufacture of the product say to do. This will just by simple ODDS give you a better finished product.
Sure there are smokers who live to be a hundred. Sure there are people who don't wear seat belts and live thru an accident.

But statistics PROVE that you are better off not to smoke and to wear seat belts. The same holds true for tech sheets and manufactures recommendations.
This is coming from someone who was resposible for claims, I was the one who came out to the shop when there was a failure. I am just passing on something that I found true. Not "opinion" but fact.
 
#10 ·
sportbikeluvr said:
3- When painting a car with plastic bumpers, do you remove them from the car or leave them on? Looking at my car it just looks like its gonna be a PITA to sand the seam but that may be the fun part of prep, right?

TIA! [/B]
Can you back the bolts holding the bumper to the car off a little so the gap opens a bit to let paint in? I've found painting them on the car to be ideal. less risk scratching during assembly and color/metalic stays right. Be ready with a floorjack or lift to get under there.
 
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