The Spray Painting Thread

[o_man_ra23]

Flouros are probably worse than the halogens when it comes to igniting thinners. To create a spark you require high voltage. The igniters on a flouro tube create much more than the standard 240V to get an arc across the flourescent gas (research HID lights). This makes them more efficient, however it also makes them less suitable for use in a combustible atmosphere.

The traditional cheapo halogens will also provide some much needed warmth onto your work area. Just don't paint them. Using a HVLP gun with low pressure should result in a low enough overspray, such that when combined with the semi-open nature of your makeshift work area won't be an issue with regard to explosive gas buildup.

[oldcorollas]

if you break a fluoro, then it will probably ignite..
and the ballasts might be in issue? not sure..
the halogens are too bright for my eyes.. adn the glass surfaces get so hot, paint dust on it melts and smokes
so i think halogens are not ideal during spraying
also, HVLP may have less overspray, but still a lot of thinners in the air, and thats what i feel is dangerous.

anyway, today i went searching..
win!
mitre10 had these for $129, maybe globes, maybe not. but had to order, couldn't say if globes until ordered = ghey.
bunnings, on sale for $99 and globes (48W!!) = $16.70 each
has nice switches and stand etc, compared to the cheaper halogen tripods (the Nelson halogen tripod was also good quality). should make sanding/painting at night easier

good points. light housing is LARGE to fit the massif 48W fluoro globes. they are diecast alloy..
there is a silicon seal between the glass and the body, so no vapours can get in, and the cables are split at a sealed junction box.each light has a switch, with silicon cover over the rocker, in a sealed junction box... plus, being compact globe, the ballast etc is inside the sealed light box
I think these will be pretty safe.
also, light... there is a LOT of light, but it is not eye piercing..
and lastly, it extends to 1.8m high, and with the tripod legs extended, close to 2m high, so will be good for roof work too
pretty happy with the purchase
now, to get back to sanding....

[o_man_ra23]

First, those seals won't protect against vapours, only liquid (low or no pressure - high pressure water will make them look like a gaping hole).
Second, the 'ballast' is a big inductor. Inductors can generate very large instantaneous voltages. The voltage is then sent to the floursecent tube through a small bit of wire. This bit of wire is the worry point for a spark, not the sealed tube itself.
Third, when compact flouros come to the end of their life, they generally go off with a bang, but that is ok, as they are designed with a nice safe relief vent to prevent them really making a mess or causing a fire. However, this still allows an ignition source to momentarily come out.

As said before, I don't think you will have worrying quantities of thinner vapour in the air (you still need high enough concentrations for it to become explosive - which you won't get in a plastic tent) so it should be safe, however the halogens are actually safer.

Might get one myself and set it up on one corner of the car, and my halogen one on the opposite corner for when I re-re-spray.

[oldcorollas]

hmmm, science thinking cap on..

lower flammability limit for toluene is 1.25%ish, upper is is near 7%
tent is about.. 3.6x3.6x1.8m = 32cubic m =~ 23500L,
1.25% of that is 293L
that's roughly 12 moles of gas
1 mole of toluene is about 92g, so 1.1kg of toluene = abotu 1.27L..

so assuming air was displaced by toluene vapour, i'd have to spray at least 1L of thinner for it to be explosive in the "confined" space...

that doesn't rule out flammabilitywhen sprayed directly at something tho but is rather reassuring


re: the seals, they are between the glass surface and the diecast alloy housing. i'm sure if there was a pressure differential across them, they would leak, but i don't envisage an ingress of vapour by diffusion past them. the housing is 1 piece, and the hole for the cable is "sealed" also, so to a first approximation, they should be "safe-ish"
they certainly are't hazardous environment approved, nor designed to survive an explosion.

so if the compact fluoro is contained within the semi-sealed housing, with no flammable vapour around it, then even if it does spark or blow, it would be ok.


we could do a test.... let one of the fluoro and one of the halogen floodlights warm up for half an hour, then spray thinner only on them, and see what happens
paint dust smokes on the halogens... so i wonder about thinner laden paint landing on them..


hmm... just thinking.. a flammable concentration of thinner in a garage would absolutely stink! imagine spraying more than a litre of thinner around the place!! smells bad enough with 2-300mls..

["Z" UTE]

Guys, do not forget the humble 100watt outdoor floodlight. Totally sealed unit, available on stands , or bolt to your roof fittings. I have 6 in my garage, 2 over top, and 2 on each side, all angled to to totally illuminate the car. Probably replaced all the bulbs twice over the years, but 25 paint jobs later, and still nil combustion.


cheers Chuck.

[o_man_ra23]

OC, I can assure you that the seals on those floodlights are NOT vapour proof. And the cable 'seals' they put on there are not even the $3 IP68 glands we use on cheap jobs, so there is zero chance that they are vapour proof.

But like you said, the concentration of thinners required in the tent to be flammable is well below what would be in there (remember that there will be leakage too, so you will need a lot more than 1.1ltr of thinners in the air to get your 1.25%)

[oldcorollas]

yeah, i had another look.. they are not that good

yup yup, wasmore worried about a stray stream of paint/thinner toward a hot object.
not so worried anymore.

heya Chuck, yeah they would do as well, especially for a permanent setup... but the bright lights hurt my eyes

["Z" UTE]

heya Chuck, yeah they would do as well, especially for a permanent setup... but the bright lights hurt my eyes

Yeah they also cast great shadows across uneven surfaces, best not to go there with the rear qtrs on the Rolla.

[oldcorollas]

ahem....

i could post a funny picture but....

this isn't the bogging thread

[oldcorollas]

hmm, not getting a big fan today.. tried 20, 25, 30psi, all about 10-12cm fan
maybe the air to aircap is leaking somewhere? edit: was probably the viscosity.. 50-55% thinner but still not enough when cold?

edit: adding a bit more thinner.. is a bit cold outside...
getting better.. only 13deg, so taking a while to flash off

fingers crossed!

woo, went pretty well. only noticed 2 stuffups..
first was a drop of water from respirator splashing onto panel during first coat
second, found 1 small pinhole...

overall tho, pretty pleased, and getting th ehang of thinner vs flow... but geez it would be easier if it was a touch warmer 12deg and 70%RH when finished..

editedit:
hi-tek spray booth.


after first coat.. can still see filler etc, but was covere reasonably well on 2nd coat

["Z" UTE]

Hi guys, someone on these forums asked where to buy walnut shell, an abrasive usede to blast paint of panels. I found a mob that advertise in Just Cars magazine. radum.com.au they seem to have a shop in most capital cities. They also have an amazing array of tools for the workshop.

oldcorolla's, you are getting there buddy, the colder weather has shut down any chance of painting for me here in Canberra for at least the next 3 months, 12 degrees hey, heat wave in my books.

cheers Chuck.

[oldcorollas]

that name sounds familiar... for garage hoists i think?

can't see the pinhole here, but a lot more consistant than last time. (and yeah, there is a bit of unevenness near the edge of the door but i cbf )

[oldcorollas]

got paint on tonight, after working hard at prepping the last couple of days...
13deg, about 60% humidity...
mixed the primer at about 600mls paint and a bit over 1L total, so thats like... 500+ml thinners
wasn't flowing properly on the panel tho

still not thin enough for those temps...
i ended up turning pressure down to 20psi dynamic, and then turned the gun down a bit further!

3 coats on roof and 2.5 on side panels.. the last pot i added extra thinner and it flowed much better on the panel, plus had a wider spray pattern....
i'll know how to correct ti next time

only had 1 spider and 1 bug try and eat the paint... plus maybe 1 cat hair? also didn7t do up the cap properly and spilled about 5 drips onto the roof goddamit....

can7t see much in pics.. looks grey

not sure how much paint i should have used for this much panel, but ended up using about 1L of paint for the 2.5-3 coats.. seemed to go on pretty thick tho..

["Z" UTE]

OC, I generally use 1 x 4 litre can of primer/filler per 2 cars, depends on how much filling is required. Rememberr most of ends up on the floor when sanding the guide coat off, so it really does not end up being that thick on the panel. I hate the swimming bugs, if I see one I use a pair of tweezers to pluck it off, and then give that area another quick hit with the primer.

Sounds like you are getting the hang of the thinners ratio's, that and gun speed across the panel with good gun setup will result in a great finish. It may only be primer at this stage, but it is great practice for the colour coat.

cheers Chuck.

[oldcorollas]

Thanks Chuck
man, tweezers would have been a great idea was so tired by the time i got to spraying it was hard to think..

whats killing me at the moment, apart from the low temps, is lack of light.
generally need to wait until dark for people to go inside (and for me to finish prepping ) and i didn't have lights set up in good position today. made it hard to see if paint was going on properly, and if i was overlapping enough.
haing the paint too thick also killed the fan width, which made overlapping hard and made for far too pany passes..
i think in future i'll stop and adjust paint iscosity until fan is big enough

i'm appreciating how important it is to see the paint hit the panel.. kinda like watching a weld pool

yeah definitely good practice! and now i know how thin it should be when it goes on (at those temps) i'll be able to spot it next time.

going to have a bit of a practice with colour doing the door jambs and openings, before hanging panels, so i hope i can get my eye in there too.

pics from today
http://i301.photobucket.com/albums/n...mg8783-sml.jpg
http://i301.photobucket.com/albums/n...mg8785-sml.jpg
http://i301.photobucket.com/albums/n...mg8784-sml.jpg
that last pic is the farked panel i've been smashing. turned out reasonable good in the end, but there is still a significant shitshape

also getting used to the Rage Gold filler.. it's good for low temps! but a not viscous enough for building when temps are not so low.. and great for filling pinholes (of which i found a few when spraying tonight )