What's making the paint go like orange peel?

[pryantcc]

Hi guys, another painting question.

I've started squirting high build primer at the Alvis and every panel requires extensive sanding with wet&dry to get rid of the orange peel.

I'm just wondering is it the way I'm spraying? (I have zero experience) or the paint or the atmosphere, or what?

I'm using 2-pack filler/primer on top of etch primer on top of aluminium. I spray on 1 coat of etch (single pack, no hardener, just thinners), let it flash off, then 3 coats of filler/primer allowing it to flash off between coats also. I'm doing it in my garage, no heating, but I've made sure it's always above 15 degrees C whenever I do it. I have also got an infra-red heat lamp to help the paint flash off between coats.
Any handy tips to ease the sanding burden?

Thanks,
Paul.

[m.thaddeus]

Hello There

It does save a lot of time and effort if the primer is flat, it also saves a lot of material as all of those bumps are wasted paint. But it does take a bit of practice to get a smooth coat of hi-build without also getting runs. The balance is about the runniness of the paint and how much you put on. Oftentimes you will find that the first few coats go on nice and flat, but successive passes lead to pudding.
One remedy is to thin the last coat so as to make it flow out into the previous.

But having said all of the above, everyone who has painted has spend a lot of time flatting out lumpy primer. One trick to make life easier is to use a slightly coarser grade of wet and dry initially and finish with the proper one. Or start by dry-flatting with 400 and finish with 600 or 800 wet.

[pryantcc]

Great stuff, thanks Martin! It's re-assuring to know that I'm not alone!

I bought your book! It's great!!

[Morrisand944S2man]

Use cellulose primer, it goes on in thinner layers, flatter, and you can thin it more than you can 2-pack. Cellulose is much easier and more forgiving to use than 2-pack, plus it is easier to sand. Overall, much better for the amateur to gain experience with and a cellulose top coat will give a much more authentic finish on your Alvis.

Besides which it is much safer to use on your home garage. Unless you have an extracted booth with air fed mask and the compressor for the air fed mask sucks in clean air, then what you are using (2-pack) is potentially lethal in the confines of a domestic garage!

[johnc]

I've also picked up a spray gun for the first time to paint my Rapier and did a lot of research into paint choice.I also concluded that for a novice in a 'domestic' situation 2 pack is not condusive to a long and healthy life! It's cellulose for me and so far with good results with the primer. I can highly recommend a book 'How to Paint Classic Cars' by one Martin Thaddeus.

[pryantcc]

Use cellulose primer, it goes on in thinner layers, flatter, and you can thin it more than you can 2-pack. Cellulose is much easier and more forgiving to use than 2-pack, plus it is easier to sand. Overall, much better for the amateur to gain experience with and a cellulose top coat will give a much more authentic finish on your Alvis.

Besides which it is much safer to use on your home garage. Unless you have an extracted booth with air fed mask and the compressor for the air fed mask sucks in clean air, then what you are using (2-pack) is potentially lethal in the confines of a domestic garage!

What would be the difference with using cellulose for a top coat compared with 2-pack?

I went for 2 pack primer because I would be using it in the colder months of spring so wanted to be sure it would harden properly.

[Grumpy Northener]

Longer drying times for the cellulose but it is far safer to use if you do not have access to a proper vented spraybooth area, and is very forgiving when you make mistakes - 2 pack is very good if you have the right workshop facilities such has a proffesional spraybooth, airfed masks etc - if you do not have these - please do not take the risks - I worked within this industry when 2 pack paint came upon the scene and a lot of guys took a lot of risks - those guys that I knew are now paying deeply for the risks taken - today with poor health / breathing problems. Play safe and stick to the cellulose products - granted it is harder work but the results are worth it.

[pryantcc]

Thanks Grumpy, I hear you loud & clear about the risks. I was really wondering about the difference in finish between cellulose and 2-pack. What is "more authentic" about a cellulose finish?

[Luxobarge]

What is "more authentic" about a cellulose finish?

It's a rather subtle thing, but 2-pack can look a bit over-shiny and synthetic. I've heard it described as a "marmalade" look. I think particularly once cellulose has settled down and been polished a few times, it will acquire a shine that is a bit more- how can I put it - "honest" than 2-pack.

I'm a fan of 2-pack BTW, it's so much tougher and more hard-wearing, but in your case I'd use celly, because 1) it's a little easier to use 2) as above it's a bit more "authentic" and 3) last but not least the health hazards!

I did the Midget in celly.

Re. orange peel effect: I've always reckoned that paint spraying is more of an art than a science, and it could be a number of things. Number one is probably paint-to-thinners ratio, but also the amount of material-to-air ratio adjustment on your gun, the width of the fan, how close the gun is to the surface and the temperature. Also the time between coats - if the previous coat has gone off completely and shows orange-peel, then subsequent coats probably will do unless you flat down. I do agree with the principle of doing the final coat with a much thinner mix though - a "flow" coat, the extra thinners will tend to "melt" down into previous coats and smooth the whole lot out. Watch out for runs though, this is a fine balancing act!

All the best with it mate - looking forward to the pics!

[Grumpy Northener]

For me it carries more of a factory finish to it and you can get some nice depth into the paint by carefull polishing - 2 pack tends give an apperance that the car has been dipped in a vat of plastic. Has always the finish to your paint is only ever going to be as good as your preperation - so my tip - is when flatting back and compounding / polishing - always work in one direction through the car i.e. from front to back - never in circles. I prepared the bodywork and painted a Jowett Jupiter through the months of Feb to May last year in a cramped dusty workshop, old paint & cheap spraygun - spent a long time flatting and polishing each panel in turn - it won 'Classic Car of the Year 2010' - so just take your time - tackle the panels one at time and you will get there - any other questions just post them up - there is enough of us out here with the answers.