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MG MGB Technical - spraying

I have had quite a bit of experiance over the years of paint spraying with celelose paint. in fact last winter I resprayed the whole of the back half of the roadster with celelose that I had. As this older type of paint is getting harder to find and it does not seem to be as good and long lasting as modern water based paints I wondered if someone could give advice on the differance in the technique of spraying this paint. Or where this info. can be found.
Trevor Harvey

I can only give you some tips on water-based, from my own limited experience.
If you are using water-based, with standard HVLP gun, then be sure and clean your gun immediately after each use , by total dis-assembly, using your standard thinner...(I use lacquer thinner)...Otherwise, some parts may rust.
If you are doing both primer and base coat/clear coat, in water base, give plenty of time to dry before any color sanding....
If you don't have a shop dryer (which most folks do not), you may have to wait 3 or 4 days, before sanding primer.
Base coat may take a few days to be ready for clear.
The clear coat comes out white/hazy looking, and will clear up as it hardens....
Since I see you are in the U.K., temperature and humidity will probably require even longer times.
I suggest that before you attempt to spray the car, you get a piece of sheet metal, and experiment with drying times and finish....
I like water-base, but it takes some getting used to.
Edward
E.B. Wesson

Trevor,
I'd be interested in how you did your spraying and under what conditions as you said it was during last winter. I intend to do my roadster but recon to have to wait until the spring for the right conditions. What sort of finish did you achieve and how much polishing did you have to do afterwards?
Steve Church

I sprayed my GT in winter in my domestic garage with cellulose. I hoovered the garage from top to bottom and then sprayed the floor with water to prevent dust. I applied two coats of anto rust paint then three coats of Hi build primer. Then a guide coat and a flat down with 600 grade paper. Finish was three coats of FlameRed and a flat down followed by one final coat. This was denibbed with Superfine paper and then machine polished by machine using Farecla G3 compound. The final finish is like glass and up to concours standards. The only heating I had in the garage was a 4kw electric one which managed to raise the temperature to 60 degrees
Iain MacKintosh

Steve.
I resprayed the back half of the roadster after replacing some rusty lower panel bits behind the wheels and rear lights.
I have done a lot of spraywork over the years and am fortunate that my father was a proffesional paint sprayer by trade and I was taught a lot by him.
I do not find spraying is to much of a problem in the winter but it is no good being in a hurry and wait for milder conditions.
Unless you can warm the workshop up to about 60 deg. apply all primer coats singularly and then leave for a few days before adding more. this also goes for colour coats. The longer you can leave between coats the better. The paint as it drys shrinks a little,if it is not allowed to dry properly,imperfections will show later, you may have seen it yourself where repairs have been made using filler and the outer edge of the filler line shows through.
The information sent by Iain,sounds good advice.
Trev
Trevor Harvey

So Trevor
Are you going to spray some water-base paint???
Guess I'm a little confused.
Edward
E.B. Wesson

Edward, Will not be doing any spray work for a while, I done what I wanted to do last winter but will keep in mind the advice kindly given by you.
I was curious to know the difference between the two types of paint.
I like to use the car in the summer and do the maintenance in the winter months, as I am retired it helps to keep me occupied. This winter it will be the front suspension, mainly cleaning and repainting.
All the best. Trev
Trevor Harvey

Recently, I asked my local auto paint shop about water based paint.His reply was "that's been & gone" I ended up with acrylic, same as the original paint which I don't think will be around for much longer. Barrie E
B Egerton

Depending on where you look the term 'acrylic' is applied to variously enamel, colour coat/clear coat, 2-pack where two components are mixed during spraying and is toxic and needs a full-face helmet with positive air feed, and water-based paint. If water-based has 'gone', what's used now? As far as I was aware the major manufacturers still used it. Originally MGBs used cellulose (laquer), changing to synthetic enamel over a period.

From what I've read cellulose polishes up to a high gloss better then 2-pack, but needs relatively frequent repolishing compared to 2-pack. Water-based seems to generate complaints of damage from bird droppings.
PaulH Solihull

My understanding is that major manufacturers are using water-based paints now, mainly due to environmental concerns with urethanes...
Acrylic enamels need a catalyst , similar to urethanes, to properly harden. The good thing about enamels, is you can make an invisible repair, whereas with urethanes, either two-part or single-stage, repairs will almost always show, unless the entire panel is repainted.
The negative with enamels, is they tend to chip more easily than clear coats.
Edward
E.B. Wesson

I have resprayed my 78B a couple of times and both times I used what I was told was the same as original. Acrylic lacquer. I figured it was easier to work with than enamel anyway, as I was told enamel takes a long time to cure and you can't easily sand it like acrylic lacquer.
I was also told two-pack is the one you need the respirator equipment for as the catalyst is poisonous. With acrylic lacquer and enamel you can do with a basic filtered mask, although a well ventalated area is advised.
I need to do some touch up work and a few years ago I was told it was getting harder to find non-water based paint. Is this true and should I also be considering water-based now or should I try and source the original stuff if possible? Aside from the cleaning of equipment after each use, are the other hassles with using water-based and is it as easy to work with as acrylic lacquer?
Cheers, Dave.
D O'Brien

Using any paint with organic solvents you need a mask that has active carbon filters, or a fresh air mask. Either way, you should not be able to smell anything.
I have a spray related query. I'm doing the body on my MGA. The outside is easy, but when trying to spray the inside there is so much reflection and backscatter, it gets quite messy! Not sure there is any cure though...?
Art Pearse

This thread was discussed between 03/11/2012 and 04/12/2012

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