Spray gun advice - Im in search of info...

[ventureoverland]

Guys,
This maybe a long post, but please bare with it... I think Ive exhausted Google and need words of wisdom from the wise...

I seem to be acquiring a list of jobs to do around the house for the mrs. Finishing / painting the jobs is my current problem.

So far I have painted some large, flat cupboard doors with white Dulux Enamel (oil based). This was applied with a small sponge roller - it took for ever for the stuff to dry but I managed to get a good, flat & hard surface. Problem is yellowing.

Next up was a large, flat, office desk (3.4m long x 800 deep). I decided to try the white Water based Dulux (Aquashield??). This was much quicker to apply but I think it dries too quickly so, using the same rollers in the same environment my finish is not at flat as the oil based equivalent. Perhaps my biggest issue with this though is the surface still is not hard (a month later). Don't get me wrong, its durable and OK, but you can push your finger nail into the surface and it does seem very susceptible to marking.

Next up is a headboard for a bedroom and then some wardrobe doors need replacing and another bedroom a refresh. Both will be white.


Ive decided that I should really invest in a spray gun and get some practice in before I need to switch my attention back to my old Land Rover restoration (that needs a re-paint). This will hopefully allow me to lay a flat, hard, durable (and ideally UV stable) paint to my projects.

Ive found that the Gunman on Youtube is excellent - at least I like his style and can kinda understand what he's saying.


I subscribe to the buy it once, buy it right mentality....


For automotive work, Gunman highly recommends the Devibiss GTI Pro Lite gravity fed gun. (My father used to do a lot of spraying and always said Devilbiss were very nice guns).

So, what Ive learned so far is there are a lot of variables, namely:
- Air cap size - TE10, TE20, TE30 (HVLP)
- Needle size 1.0mm - 2.0mm

These variables all seem to work together and are based largely on the requirements / viscosity / type of paint.

Gunman says that for a home guy wanting a good all-rounder, a TE20 with a 1.4mm nozzle is a good place to start. That means I could buy the Gti Pro Lite as its available with all 3 air-caps and nozzle sizes of 1.0 - 1.4mm.

I have a decent sized compressor and I reckon the TE30 (HVLP) air cap would still be OK, but more inclined to opt for the more conventional TE20 configuration and reduce air flow requirements).

Questions:
1. What paint to use for wood / ply / mdf? (This seems to be where Google is failing me)
2. Are 1k paints the same as acrylic?
3. I understand the safety concerns about spraying 2k at home - For occasional use though can 2k paints be sprayed (outside in the garden) with a decent respirator & new cartridges or is it a complete no-no?
4. I remember as a kid my dad always sprayed his cars with cellulose paint - its still readily available in the UK, but doesn't seem to be here? Is cellulose an option here?

Do you guys think the TE20 & 1.4mm would be a good place for me to start? I can always buy smaller nozzles or the TE10 cap if needs be when I come to the car paint. I cant see myself having a need to blow really thick paint onto anything (assuming thats what the 1.8mm & 2.0mm nozzles are for).

Any suggestions, pointers and advice welcomed...

Jon

[wheelinround]

Jon I feel for you and your predicament, if you have been doing this painting through Sydney's recent weather conditions it will only make painting that much harder to accomplish what you are after. Ambient temp, moisture ( I don't care what the instructions say temp can be down to or up to. they are only a guide) You have to also consider Northern Beaches has a disadvantage not only for the surrounding air but moisture content in the material and that will be effected on a daily bases and overnight. I won't paint anything if temp is close to 15C add to that moisture in the air or cold snap and you get dampness.

As for spray guns I'll leave that to the guys who have far more modern systems than I have (I still won't spray if moisture be it low rain or humidity is about)

Just read your questions.

1 Somewhere on here the question was asked re-painting MDF some excellent replies came through. For wood & ply all sorts depending on what your after.
2 1pk paint comes in enamel & acrylic types
3 2pk is not just about respirators it is harmful to the whole body if not covered even if sprayed out doors.I started spraying 2pk when it was relatively new on buses & coaches wearing just a mask and covered in vasoline and overalls in a shed. Today it must be done totally indoors except for small areas and even then the risks are high.
4 Nitrous Cellulose is usually clear these days or such as Hammer tone still available here.

Interior paints are thicker than auto paints so just thin them more.

Ray

[david.elliott]

Wow, just been there big time. I paint kitchen cabinet doors that I make to order often with and only with oil based enamel.
I build the doors from MR MDF, that's a must. Even then I get the odd one that bows. I also line the inside of every door with liner laminate applied with contact adhesive.
Also 1 or even two light coats of oil based undercoat is necessary, giving a rub with maroon scotchbrite in between.. then when fully dry two good coats of quality oil based enamel. Again rubbing between both... I have found on several other projects around the home that the water based "enamels" stay "sticky" for a long time..even a year on...

Last one has been a nightmare though. Dodgy paint from an otherwise great past supplier. I figured it must be down to me and persisted. One Sunday morn in desperation shot down to the local hardware and got a litre of another brand. Problem solved. A reason for thinking it was something I was doing was that the dk grey and white both had the same issues...turns out there is only one base for satin enamel so the base was flawed.

I had bits in it and it was taking two days to dry...and more. Could not get through a stocking even when thinned 25%.

I have a cheapy Scorpion gravity fed gun with a 1.4 tip. With HVLP it's better to err on the less side with the pressure coming from the compressor than the more. Too much ends up atomising too small and it just drifts away...
I got a moisture trap on the compressor and one with two connectors that goes between the gun and hose. Cannot get too much moisture out! I like to get the pieces out into the warmth, not hot, before spraying, just to take the chill off them. If you have room take the opportunity to do a very light "tack" coat on what you can layout, and when that's going off put the final coat on, assists with stopping runs. I spray outside, somedays bugs can be an issue.

Recently my filling of brad nail holes has been a problem with Timbermate. When raw I fill once, then sand flush, fill again and sand. Then undercoat, which seems to make the appear again. Seems like every coat of paint makes it shrink some more. Moving to auto body filler for the next ones..

[wheelinround]

Note about compressor and line moisture its best to drain the tank regularly daily if used that much. As moisture accumulates it reduces the volume of the tank as it does.

[rob streeper]

Hi Jon,

I do a lot of different types of spray coatings and thus I have a number of different spray guns. Below is my SATA 95 set for medium to larger jobs. On the left is a suction feed with a 2 mm spray tip. I use this gun for application of primers, lacquers and the thinner oil paints. In the middle is a gravity feed HVLP with a 1.7 mm spray tip. I use this one for medium weight oils and water based enamels with Floetrol at ~10% v/v. The rightmost is a pressure feed standard pressure gun with a 1.2 mm spray tip. This gun sprays the heavier acrylic enamels and high solids oils that are becoming more common with increasing environmental regulation of VOC releases.

SATA NR95 collection.jpg


I have three NR95's primarily to allow interchangability of parts and accessories, this is one of my favorites. This tip, a 1.6 mm, allows one to spray paint at 45^o to the needle axis - great for spraying harder to reach areas like the tops and bottoms of installed cabinetry.

SATA 45 degree tip.jpg

I have smaller guns for smaller work of course but these three allow me to apply just about any sprayable coating out there.

Cheers,
Rob

[ventureoverland]

Thanks guys for the replies.

The more I read, the less I feel I know and the more I feel I should shy away from 2k paints, at least for now. Notwithstanding the safety concerns, the general opinion is that its harder to get good results in the hands of a novice (like me!). Also, I read somewhere that the high gloss, 2k paints don't look all that flash on an old beaten up 1950's Landy.

I think my next port of call will be the paint suppliers and have a lend of their ear!

Thx
J

[soundman]

First and most important ...... don't let this spray gun thing get over complicated.
Second pretty much nignore any brand recommendation from an overseas web site.

Unless you are some sort of professional you will never have to make a decision on needle size ....... you will buy a gun and pretty much use it as it came with the needle it came supplied with.

In Australia the go to basic Gun that everybody uses, most people start with and a lot of mid range trade users never move past is the "Star S770".
This is a basic trade quality suction gun and will pretty much spray anything from glue to nitro reasonably well. From memory mine came with 1.8mm nozzles.

These days if I was to have one spraygun it with be a HVLP gravity gun ...... I have a couple of Porter Cable branded guns that I recon are made by Star.

The gravity guns are much easier to clean in general have much better spraying efficiency because they can run a lot less air pressure .... bang for bucks ya cant go past Star, though there are some pretty good generics out there.

The single biggest thing you must consider if you want to spray with any sort of quality is a second reciever for your compressor ....... that is a secondary tank after your compressor and before your water trap.
The second reciever will allow the air to cool and drop most of the water and oil before it gets to your filter reg ...... when the air gets to your filter reg it will be cool and the filter reg will work effectivly removing what moisture and oil is left.

This second reciever can be any tank that is capable of handling the pressure ...... I use a tank from a dead compressor ....... the air needs to go in one end and come out the other.

cheers

[ventureoverland]

Thanks soundman, advice appreciated.

The single biggest thing you must consider if you want to spray with any sort of quality is a second reciever for your compressor ....... that is a secondary tank after your compressor and before your water trap.

Must admit, Ive thought about this a couple of times before and could never bring myself to pull apart my old, small 2.5hp compressor to use the tank. Maybe now's the time...

On the other hand, does anyone know how thick the base of an 8.5kg gas bottle is? Would it accept a 1/2" or 3/8" BSP thread for an air connector? I seem to have acquired 4 or 5 of them, all empty.

Also, Ive just been to the local Dulux Trade centre - they advised Dulux "Enviropoxy WBE"- Water based, 2 pack enamel. Apparently it dries hard, won't yellow, is sprayable and perhaps most importantly won't try to kill me like 2k paints - so seemingly meets my criteria. The only downside I can see is that its only available in 4L tins and perhaps the cost (yet to ascertain that). Primer / Sanding sealer is bog standard acrylic paint.

http://www.duluxprotectivecoatings.c..._wbe_pc295.pdf

Has anyone used this stuff before?

The chap also said that Rustoleum make a furniture restoring paint product that maybe suitable but didn't have any details on it.


Now to check out the Star guns.

Thanks
Jon

[Arron]

Questions:
1. What paint to use for wood / ply / mdf? (This seems to be where Google is failing me)

Do you mean paint or clear coat ?

2. Are 1k paints the same as acrylic?

No, can be sovent-based as well. It just means anything but 2pak.

3. I understand the safety concerns about spraying 2k at home - For occasional use though can 2k paints be sprayed (outside in the garden) with a decent respirator & new cartridges or is it a complete no-no?

I think its pretty close to a no-no. As far as I can work out its legal to do so in NSW (but don't rely on my advice because its hard to work out) and a high quality line-fed respirator and full body coveralls (because there are always spills and splashes when spraying) will help protect your own health, but its the neighbours you need to think about. There will be spray drift and there are a lot of people around with sensitivity to chemicals which can be set off by tiny amounts. My BIL is an example (acquired sensitivity after too long in the panelbeating trade) - and this became an issue when an ignorant neighbour sprayed a caravan outside.

Also, think about kids with asthma.

There may be more generic laws on not being a nuisance to your neighbour or not endangering their health, not sure whether they might cover.

I think if you need to spray 2k occasionally then the best solution is to hire time in a spray booth for a few hours when you need it. That will allow you to set up for something a bit less toxic.

The other problem with spraying 2k outdoors is that its not particularly fast drying, so you have all the problems with dust settling, kamikaze gnats etc. For spraying outside a booth it helps to have the fastest drying product available, something like precat lacquer that basically dries before the dust and bugs can find it.

4. I remember as a kid my dad always sprayed his cars with cellulose paint - its still readily available in the UK, but doesn't seem to be here? Is cellulose an option here?

Its still around - nitrocellulose lacquer. Its not used for cars much any more but in its derivative form (precat lacquer) is still the most popular clear finish for smaller furniture outfits or places that don't have industry-standard spray booths. Precat lacquers are nitrocellulose lacquers which have been modified to have some catalytic reaction rather then relying on straight solvent evaporation. This makes them tougher, though still with the advantages of lacquer (fast drying, coats melding into each other etc). Two example products are Mirrotone (Mirrorlac) and Wattyl Stylewood.

On the guns side. The devilbliss you mentioned appears to be the go-to gun for most pro auto-finishers at the moment. A 1.4 for general use and a 2.0 for primers and spray putty would be the normal starting point. If you wanted a dedicated gun for the spray putty then it might be a good idea to buy a cheapy from super-cheap autos - you are not usually worried about finish quality with primers.

I concur with Soundman too - Star guns are great value for money. I have some hvlp Star guns and they are holding up well.