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MG Midget and Sprite Technical - Guide coat

Guide coat next. But what to use? I'm doing this in celly. Does it matter what I use as a light guide coat before flatting off. Something in a rattle can would be easiest.


GuyW

You should be able to get some black primer in a rattle can, just give it a very very light,see through dust over. then you'll be able to pick up on any issues easier when you block it off and it gives you a guide as to how far you've rubbed preventing the oh bugger I've gone through the primer issue--
Primer is probably best for this as it's a bit softer and rubs back easier compared to topcoat.
William Revit

Exactly what I do Willy. I should add though, -- when I can be bothered. Lol.

Lucky for me mine is oe white. Yours is blue right Guy? So it'll show more if you don't flat it.

Btw, pleased to see you decided against turning it into a parts bin. I didn't think you really would even if it does stack up economically. You've had it too long, put too much time/effort into it over the years, plus used/abused and enjoyed it too much to scrap it for a fist full of dollars. Lol.

Or even a few dollars more. 😉

https://youtu.be/HjjDOdaFZg0?feature=shared

https://youtu.be/vgghuqh41pM?feature=shared

https://youtu.be/9fEndGSMu_c?feature=shared

anamnesis

Looks good Guy, can I book mine in with you when you've finished? :)

"Trev's Blog" was a good Youtube channel for bodywork, doesn't seem to be very active currently but back catalogue is still there and covers metal shaping, fabrication, preparation and paint.
AdrianR

Thanks. Black primer sounds like the stuff. I was just slightly concerned that modern rattle can paint (acrylic?) might react with my cellulose based primer.

Incidentally, so far been partly on bare metal, (repairs), part on very sound previous 2K Some light skims of 2k body filler, full overcoated with two coats 2k epoxy primer, then 2 double pass coats of celly primer. Quite a lot of rubbing down and refilling blemishes with celly putty as I go. Its a slow progress outside job with variable Cumbrian weather and grandkids thrown in the mix to complicate things a bit!
GuyW

Make it look great again Guy, like it was in 2007 during our Scottish tour!

Im actualy doing part of this tour again in a couple weeks.
Sadly not in the midget but now in the 1978 jaguar xj6 with wife and kids :)





A de Best

Guy--if you're worried about reactions you could get your local paint shop to poke a little black tinter into some of your grey celly primer, you only need enough to change the colour a tiddle so you can see it when you're blocking it off --- even so, just a thin dust coat is all you need then you'll rub most/all of it off anyway
William Revit

I need to improve on my paint spraying quality for the next primer coat. It didn't matter for that last primer coat but it wasn't spraying cleanly and dried to a gritty surface. Now all flatted smooth and ready for what should be the final primer coat before some colour.

But what would cause it to go on and dry like that? What should I be looking to change to get a better final coating?
GuyW

What thinner are you using? In this weather it should be slow thinners so it doesn't flash off as quickly. Of course you may be being timid and not spraying a heavy enough coat for fear of orange peel or similar and it just isn't enough for it to flow out.
David Billington

Just a standard thinners, David.
Its warm and dry here, but not as hot as in the south. 24 degrees today. Are you thinking that the paint is drying before it hits the panel? Or perhaps that the surface I am spraying onto is too hot?
GuyW

Yeah I agree. Drying in the air before it hits the car. More thinner. I thin celly 50%. But I use a pop pop electric gun, not a proper compressor.

I use premium celly thinners. It's not that much more.

Red nose there Guy. Were you on the whiskey, or was it the sun? 😉

anamnesis

Bit hard to say without seeing it but yeah maybee the surface 'might' have been a bit hot but more likely the primer was too thick or the pressure too low not atomizing the paint enough, so yeah more thinners, and wind the pressure up to 40 or so and wind the gun up so you get plenty coming out and get back off it a bit so your spray area is larger and blow a big mist at it
William Revit

Thanks. Its a high build primer and even at a 50:50 mix is still quite thick. I am using a pot gun (not gravity) and probably need to turn the pressure up a bit. It did improve a bit as the level went down.

Next coat should be final primer and I want to try and get a finish that only needs a light rub over before first colour coat. Plus this is all experimentation for the top coats.

I do have some premium thinners, bought for the colour coats, but I might try that. When ordering these paints I thought the Premium was only a few pence more at first, until I realised that was for a litre tin, not 5 like the Standard!

I have sprayed quite a few part and whole cars over the years, but its always a learning curve to regain after a couple of years. Paints have changed and even now going back to celly it seems different. Plus current conditions, though should be ideal, warm, low humidity, not too breezy it all impacts what you get.

Amazing, Arie, to think that trip around Scotland was nearly 20 years ago! Not so sure it would be as good now though with over publicity as the NC500 and overrun with giant campervans.
GuyW

Ah right. Hi build primer. I thin more than 50%. I've had that behave exactly as yours at 50% in 'warm' weather too.

So bloody expensive those small tins of celly. I buy 5lts, and just keep what I don't need at the time. I use standard for cleaning.

Dumb question I know, but what is and how does the gravity gun work? An elevated tank of paint attached to a feed hose?

Edit. Just looked it up. Compressor, but gun has paint cup on top, as opposed to under the gun.

I was imagining you filling an elevated tank'🤣🤣🤣.


anamnesis

Guy,

"It did improve a bit as the level went down."

That makes me think you might have been letting it sit in the paint reservoir for a bit. IME high build primer needs to be used quickly or it can start to settle and get thicker at the bottom. As it's suction feed it should get harder to draw the paint as it goes down due to the increased height it has to lift it, although in practice I've not noticed.

Looking earlier it looks like the choice of thinners is reduced compared to when I was spraying it more often in the 1980s and less in the 1990s and using the likes of International and PPG. HMG lists a few https://www.hmgpaint.com/products/10/classic-car/9/thinner and mentions that standard thinners is reclaimed likely why it's cheap compared to virgin. I mainly use the standard thinners for parts and spray gun cleaning.
David Billington

Finished flatting off the guide coat layers and done another primer coat ( 2 at about 20mins). Much better this time. I diluted a bit more and upped the gun pressure. Adjusted for a heavier spray and resisted the temptation to get too close.

Looks quite good in grey. Matte Grey is very 'on trend' for Audies around here. Or at least with the dealers coming up on their day trips from Manchester.
GuyW

Just put some clear coat on it now Guy as gloss primer as I like to call it seems all the rage with everyone now. I can't for the life of me see why it's so popular. Its seems to be the "new" silver, an equally horrible colour in my opinion.

Trev
T Mason

Guy
I've frequently had problems with the "gritty" finish you originally had, both with primer and colour coat (celly). I too was spraying outside (usually 50:50 ratio) and came to the conclusion that the panels were too hot, causing the celly to instantly dry as it landed on the surface. Of course, you can sand the paint and it goes smooth but you're wasting paint, especially expensive colour coat!

So I tried spraying single panels at a time with the car in the shade of the garage, hence cooler and that gave better "flow" of the paint. Even so, until the paint hits the panel I'm never sure how it'll turn out and it can be very frustrating. I have found that touching up with a pre-mixed aerosol (same paint) always works well. presumably because it's mostly thinners. So for final colour coat I have more thinners maybe 70% which works better. I've also had problems with the colour "sinking" into previously filled areas (under primer of course) so you can see those areas when viewed from certain angles. But, of course, I'm a complete amateur trying to achieve something that a pro has taken years to perfect. Spraying isn't easy in my experience!

But at least one can stand back and say "I did that and it's good enough and the best I can do".
Bill B

I do know that when I originally sprayed this car I did it outside in celly with much the same type of equipment as now. That finished and lasted very well. I remember I put 14 coats of paint on it! Although they were very light and the last coat was almost pure thinners! Someone advised me that if applied immediately after the not yet dry previous colour coat it would flow and produce a gloss finish. Which is exactly what it did, so none of the usual cutting and polishing normal with celly.

Slight diversion from car stuff to fixing the roof this afternoon.
GuyW

Guy-- don't forget, specially now you're using more thinners---allow plenty of drying time between coats, as in really span it out and overdo the drying. Otherwise the thinners gets down into the previous layers and when you get another coat on early the thinners gets trapped down there and softens the base causing large cracks next year when it all dries and shrinks back--Probably more of an issue with top coats that harden off more quickly- you're probably spoilt by the good temps you've got plus the fact your base is 2pak relieving the issue a bit but just keep it in mind and don't rush---
Cheers
willy
William Revit

Thanks Willy
GuyW

This thread was discussed between 10/07/2025 and 14/07/2025

MG Midget and Sprite Technical index

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