Calling all paint experts - is this a good idea? "paint and cure", good answers. - PeachParts Mercedes-Benz Forum

Stretch · #1 03-05-2010, 05:59 AM

Dear All,

I've just sorted out my air compressor and paint gun etc and I was wondering if it was worth my while using a curing lamp on the panels of my 300D that I wish to repaint.

I can hire a lamp for quite a lot of money, and I can buy one for even more!

However, is it worth while borrowing a friend's sun tanning lamp as an almost as good alternative. I guess it doesn't produce as much UVA(?) but as a cheaper option would be any benefit from not curing at all?

Your expert guidance would be greatly appreciated.

jmk · #2 03-07-2010, 06:33 PM

Forget the UV lamp. Coatings you buy in the store do not cure by UV. Anyways, you do not want to mess with UV cure coatings. The good ones are incredibly toxic, the bad ones do not work.

If you spray the parts and keep the car out of the weather for a month, then there really isn't an advantage to baking them. If you want to drive off and take the car to a car wash the next day, then there is great benefit in the heat lamps.

I would spray and be patient myself.

Stretch · #3 03-11-2010, 02:02 PM

Thanks for the advice jmk - I'll be patient too.

cjbrown · #4 06-04-2010, 01:17 PM

I've been painting as a hobby for almost 40 years. My favorite single stage paint is dupont centari. With a cross-linker hardener it cures over night and can be wet-sanded and polished the next day. Mar-hyd high-gloss hardener works great and is half the price of the dupont stuff. You tailor the reducer to the temperature, but certainly should be 72 or so or above, up to about 85. Heat lamps or a heater will accellerate the curing/drying process. The solvents evaporate pretty quickly, like tack free in about an hour, and the hardner is a chemical process that continues for a few weeks. Centari is so hard that once it's set up hard is quite difficult to polish. Should be done while it's still soft, like next day. That's always how I've done it and my paint work comes out like glass.

You can't buy centari in calif any more due to the idiots at CARB. But you can still buy it around the country. Hands down THE BEST single stage paint money can buy.

For a carb compliant paint their chroma-system also works very well, but costs 3-5 times as much. Dupont has a budget line under NASON that works quite well but the color matching is horrible. It's fine for an overall or a complete panel, wheels, rockers, etc. Just don't try to match anything existing. And it's really cheap, holds up reasonable well.

Stretch · #5 06-04-2010, 01:24 PM

Hey cjbrown - thanks for the really helpful information. I'll see what is available over here in Europe. I must say that is a great first post (much better than mine) - welcome to the forum!

cjbrown · #6 06-04-2010, 01:34 PM

Oh, (blush) thank you. I've been browsing and have a lifetime of experience painting and detaing cars, so thought I would chime in.

I'm sorry, I didn't realize you were 'across the pond'. But yeah, I have no idea what's available over there. I would think Dupont, as big as they are, would market their paint product in Europe. Your local big-city body shops that refinish high-end cars may have some suggestions as well.

Thanks for the welcome!

Stretch · #7 06-09-2010, 07:51 AM

I've done a bit of searching about and Dupont make the MOTIP brand over here - just in case any other European wants to know.

jmk · #8 06-11-2010, 05:17 PM

DuPont also bought out Herberts in the '90's. That is DuPont's European division, though they sold OEM there before buying Herberts.

Hey-Hof · #9 06-11-2010, 09:56 PM

CJBrown is on the money with the Dupont Centari. I've been using that stuff since around 1983. And no, you cant get it in Cali anymore.

Be patient with your paint job. Allow all primers to dry thoroughly. If you get right into the primer sanding before all solvents have dried and evaporated, the sanding will look and feel smooth, but, actually continue to shrink and cause the paint to suck into these fine scratches making your paint job look bad. I usually allow primer to dry a full week before I get into the final sanding process. But, allowing the primer to dry so long, it kind of loses its pourus nature and will need a primer sealer applied immediately prior to painting to ensure proper bond between primer and paint. I always like to apply a clear coat even on a single stage paint that does not require the clear coat to make it shine. Reason being is that final polishing comes out better and allows future polishing in case of minor scratches or problems. If you wet sand on a single stage paint, you actually remove paint and make your paint job thinner and it wont last as long as if you also applied a clear coat. I stay away from straight enamel paint since Centari is not available anymore and I spend a little more and use an acrylic urathane (did I spell that right?). I dont like any of the other straight enamel paints available. I like to wait a day or so before I wet sand and polish to allow thorough curing. Dont wax your new paint for at least one month and when you do, use a soft micro fiber cloth. That was a whole lot to say dont bother with a lamp. Follow the directions on all the products you use. Ask questions if you are note sure when using a new product. Have fun.

cjbrown · #10 06-12-2010, 01:45 AM

Hey, another old-time painter.

My favorite sealer was Velva-Seal. Used to be a solvent based undercoater and then it went water-based. I hate water-based paints. Like painting with water color.

But nonetheless, it gives a uniform base for the finish coat and seals all those pores and sanding scratches. Paint should go on smooth so color sanding and polishing is just a surface finish for a glass look.

Nobody paints like this any more.
Dupont's chroma-color/chroma-clear system is a good voc compliant product, I may have mentioned this, but it's about five times the cost. Nice hard durable finish though.

I'm not a good enough painter to get by with a thin clear coat to polish, so my single stage paints get polished pretty good. Yes, I have rubbed thru a finish coat getting it to shine.

Painting is an art and a fun endeavor for the patient individual that is willing to learn the finer details. Very satisfying when you can take your picture in your reflection.

The industry keeps marching on in technology and it's hard to keep up unless you're a pro. But they do publish good technical information to help you get with the new finishes with success.

It's very hard to duplicate the finish MB put on their cars. Porsche too. I had a 76 911 in or around 86 that I bought from a guy that had broken his arm playing tennis or racquet ball. It was pretty oxidized and looking worn. But a good buff out brought out a finish that was as stunning as new. Learning paint polishing techniques is almost as important as laying down paint. That's a whole 'nother topic altogether.

EDIT: And while you can't buy centari in cali anymore, you can have a friend or relative buy it in AZ and ship it to you. And no one with a commercial paint booth will let you shoot it because CARB comes around and takes samples off their exhaust fan screens. If they find banned paints they fine them big-time or shut them down. But it shoots great in your garage.

EDIT2: BTW, it's spelled urethane. An acrylic enamel like centari with a cross-linker harder chemically sets up just like a two part paint, or a urethane enamel.

Mar-hyde makes a great high gloss hardener that is half the cost of duponts hardener, a must for acrylic enamel to make it super durable and fuel proof.
A lot of people used to shoot hobby cars with Dupont Imron which is a linear polyurethane finish, was developed for the aircraft industry. But it can't be polished and is extremely hard like epoxy. Also outlawed by california air resources board. Funny, a rusty car will literally rust out underneath Imron and leave the shell in tact. They get to be like paper mache.

Stretch · #11 06-12-2010, 04:35 PM

Quote:

Originally Posted by cjbrown

....

Learning paint polishing techniques is almost as important as laying down paint. That's a whole 'nother topic altogether.

...

It might be slightly off topic but what would I need to start? If the art is to do both - now seems like a good time to start learning to polish as well!

Stretch · #12 06-29-2010, 01:48 PM

Here's a good link

http://www.mig-welding.co.uk/spray-painting.htm

cjbrown · #13 06-29-2010, 02:54 PM

That's a great tutorial on painting, good stuff there.

I guess I forgot to respond with some help on buffing and polishing. Without going into a huge dessertation as a how-to, there are also some good online sites with information on this subject. Here are a few off the top of my head:
www.griottsgarage.com
www.topoftheline.com
http://www.chevyhiperformance.com/tech/paint_body/car_care/0403ch_color_sanding_buffing_tech/index.html
(this is a very good how-to on buffing paint with wool wheels.
It also seems to me there's a sub-forum here on detailing with some good tutorials on polishing paint. I think there's some good stuff on the mbca forum as well.

Do a google search on 'how to buff paint', lots of sites come up.

Just a few thoughts here...
My technique comes from the old days of lacquer and acrylic paints. As I mentioned I prefer single stage paint systems as they are easy to shoot, quite forgiving, and inexpensive. I have used some base-coat clear-coat systems and it's not much different, just that you have a lot of clearcoat over the color instead of lots of paint color.

I still use course and fine wool wheels on a rotary buffer. Foam pads, polishes, and systems are all the rage now. But good results can still be gotten from the old way, and like everything else it's cheaper too. WEN makes an inexpensive rotary buffer, adequate for hobbiest/home use. They're under $100 whereas a Porter-Cable, DeWalt, or Milwauki can run well over $200. A couple of wool wheels and polishes, and you're good for several cars/projects.

It is very difficult to get the same results by hand as can be done with a power buffer. However it's best not to try to learn how to do it on your pride and joy. Depending on how aggressive your buffing compound is, it can be very easy to burn right through the paint on corners and edges. So part of the technique is learning to control the wheel so it's not buffing across an edge, panel seam, or corner. Practice on the nieghborhood beater, learn how to get high gloss out of flat paint, and practice, practice, practice.

My favorite polishes and chemicals are by 3M, but there are many others that provide quality products. 3M caters to the body-shop industry and therefore has a wide range of products to suit the various requirments. You only go with as aggressive of a polishing compound as is required to restore the finish, and 3M has a whole range of them. Scratches and orange peel can be wet-sanded with progressivley finer paper to 1000-1200 grit which can then be polished to a high gloss. The more defects in the paint the more aggressive your compound. 3M makes it easy, they rate their products by the level of defect it will buff, such as sand paper grit count, haze, oxidation, etc. The same process works on fiberglass, have done a bunch of boats too.

Once your paint is glossy and free of defects, you then apply a glaze/sealer product which also serves as a very fine polish and swirlmark remover. Top off with carnuba or a synthetic wax product.

Be happy to answer any specific questions as they arise. I learned detailing, restoration, and painting starting in the mid-70's. Lot's of projects over the years!

cjbrown · #14 06-29-2010, 05:49 PM

I was doing some more web surfing for paint buffing and found this:
http://www.gmtips.com/3rd-degree/dox/tips/paint/buff/tools/tools.htm

Details on the right tools and materials, techniques, etc.

Too bad their demo car wasn't a benz instead of a vw.

Stretch · #15 07-05-2010, 02:23 PM

Thanks very much for your input Chris. I'm slowly getting my stuff together. I've got a better than average compressor and a few in line filters that are meant to remove oil. I've got two spray guns to experiment with. I'm just finishing off loads of work rebuilding the suspension on the car (front and rear) which will eventually mean no more shot blasting - so I can finally clean out the garage and make it dust free. The plastic sheeting has been bought.

I'm gonna respray my boot lid first and if that comes good I'll then move on to the doors.

Thanks again for your help