Applying Cold Gal with a Spray Gun?

Dear Gents,

Got up on the roof the other day with some Cold Gal and the temperature leading into Summer was such up here in Bashville that the stuff was skinning over while still in the can and virtually drying on the brush between the can and the roof to the point that the tealeaves were telling me by smoko-time that "There has to be a Better Way..."

I did a bit of searching and there's one particular product aimed at corrosion that besides it's chemistry, also uses viscosity (or lack thereof...) to allow it to soak down into the rust (rather than just sit on top of it) with apparently good results once a couple of coats are applied so that it also ends up covering the rust.

So I ended up thinking "Well, I've already shelled-out $35 for half a litre of Cold Gal, so I'm not going to track down that other stuff. I wonder if the Cold Gal can be sprayed?..."

Have any of you tried this using a compressor and a low pressure gun? My gun (1.5mm nozzle) is one of those nasty things that you get thrown in along with a few other nasties when you buy a budget-priced compressor. Can't quite remember whether the brand was "El Cheapo" or "Le Cheapo" :roll:... Anyway, the main problems as I see it would be:

1) Stopping the zinc and any other solids from settling to the bottom of the Paint Tank once the stuff was thinned (with Premium Thinners) to the usual consistency of milk.

2) Achieving acceptable atomization if the stuff wasn't thinned very much in order to prevent the previous problem from occurring...

This will be my first spray-gun job for what it is worth, but my gut feeling to begin with is that the needle will have to be all the way back and out of the nozzle to get the stuff through, but I am not sure whether the stuff would still atomize if I did this. Advice on both the Paint Flow and the Air Flow settings would be appreciated.

Closing left-field question: Does anyone know something that will thin Acrylic House Paint that has a little bit of flash about it (maybe Metho...) so that I can practise a little with something cheaper than the Cold Gal...

Many Thanks Fellas,
Batpig.

Gidday Batpig :)

Just a side note to make sure you Rig yourself up with some Good personal protection Gear. Zinc is an accumulative poison (Im a welder n at trade school were taught the fumes from gal is nasty stuff to avoid when welding)

Make sure u got a quality respirator Zinc does nasty stuff to u if it gets in your system......

Good luck with the spray job!

Regards Lou

Batpig,

have sprayed Zincanode 2000 and Galmet through a conventional gun with 1.5mm needle and Hammer Tone/Amerlock through a pressure pot.

I have never thaught too hard about all these issues you have come up with, just spray it on!

The cold gal I have says it can be sprated Its "Galmat" and to use their thinner. the material you have should be an enamel so turps will work, don't use fast drying thinner such as lacquer ones if thats what you mean by 'Premium."

The idea is to coat the metal with a thick coat of zinc which has been thinned with a minimum amount of solvent. The metal particles are so heavy I would think thinning it down enough and spraying it would not only not work well but may not even work at all. If you can get it to form a film you will have to increase the number of coats to compensate for the thinner layer.

You will have to reduce the cold gal down a lot to allow it to spray, if the gun you have is a proper low pressure gun ( one that diverts some of the air into the pot which is sealed so it can be pressurised) you will be able to spray it fairly thick (think cream not milk) but if not you not only will have trouble getting it out of the gun even though its thin it will need a lot of air pressure and you will blow the material all over the place and waste a lot in overspray ( over 50%) you may even cover areas around where you are spraying with overspray as the material dries slow so overspray might end up over the neighbours house (or worse) if their is any wind.


If the gun has its pot underneath put in some marbles or ball bearings and keep shaking the mixture as you progess with the spraying. This will help keep the mixture in suspension as it will settle fast. This is done to stop paints with aluminium flake so zinc will be even worse. If its a gravity feed gun (pot on top you may be stuffed as the zinc will collect in the passage way and block of the flow.

I don't think the zinc itself will be a problem regards poisoning, zinc is used for water tanks, roofs, pipes etc and even as a sun screen but the fumes from it being burnt are bad as New Lou said. Still wear a good mask. and cover up. AS its recommended to spray on the tin it must not be a problem.

Thin the acrylic house paint with its normal thinner (which is probably water) if you can spray that you can spray. First time users of spray guns are often given one full of water to get the idea of how to do it before they get to waste paint.

I think Lou is overreacting a bit to zinc. Zinc is an essential part of our diet and it does not accumulate in the body (hence then need for it in our diet).

Having said that however, very heavy exposure to zinc (eg if you are doing a LOT of welding of gal) can be toxic and lead to some short term problems (nausea, vomiting, etc) ... there is some debate about the long term effects.

You should still wear a suitable mask when spraying as there is lots of other stuff in the paint that can be harmful.

Heres the Cold GaL Material Safety Data Sheet...........................

<table valign="top" border="0" cols="9" width="100%"><tbody><tr valign="top"><td colspan="9">HEALTH HAZARD INFORMATION</td></tr> <tr valign="top"><td colspan="9"><hr width="100%"></td></tr> <tr valign="top"><td colspan="9">Health Effects</td></tr> <tr valign="top"><td colspan="9"><hr width="100%"></td></tr> <tr valign="top"><td colspan="2" valign="top">Acute - Swallowed</td> <td colspan="7"><samp>Moderate irritant. Slightly toxic. Upon aspiration into the lungs, chemical pneumonitis may develop.</samp></td></tr> <tr valign="top"><td colspan="2" valign="top">Acute - Eye</td> <td colspan="7"><samp>Irritating to the eyes. Signs of irritation include redness, soreness and tear production.</samp></td></tr> <tr valign="top"><td colspan="2" valign="top">Acute - Skin</td> <td colspan="7"><samp>Mildly irritating to the skin. Signs of irritation include redness, itchiness and eventually cracking of the skin. Irritation usually only occurs after prolonged, repeated skin contact and is due to the de-fatting effect on the skin of the product. May lead to the onset of dermatitis. Can be absorbed through the skin with resultant toxic effects.</samp></td></tr> <tr valign="top"><td colspan="2" valign="top">Acute - Inhaled</td> <td colspan="7"><samp>Harmful by inhalation. Irritating to the respiratory system. Vapour inhalation may lead to headaches, dizziness and possibly nausea. High levels of exposure may result in central nervous system depression, loss of coordination, impaired judgement and, if the exposure is prolonged, loss of consciousness and possible death.</samp></td></tr> <tr valign="top"><td colspan="2" valign="top">Chronic</td> <td colspan="7"><samp>Skin irritation may occur after prolonged, repeated skin contact and is due to the de-fatting effect on the skin of the product. May lead to the onset of dermatitis.</samp></td></tr></tbody></table>



Play it safe.

http://www.septone.com.au/msds/AUCGP500.htm

Regards Lou:2tsup:

I'm not trying to downplay the dangers of the paint, just the "dangers" posed by zinc. From the link to the MSDS ...


<TABLE cols=9 width="100%" border=0 valign="top"><TBODY><TR vAlign=top><TD colSpan=2>Ingredients</TD><TD width="30%" colSpan=2>Name</TD><TD>CAS</TD><TD>Proportion</TD><TD></TD><TD colSpan=2></TD><TR><TR vAlign=top><TD colSpan=2></TD><TD width="30%" colSpan=2>Ingredients determined not to be hazardous</TD><TD>-</TD><TD>60-100 %</TD><TD></TD><TD colSpan=2></TD></TR><TR vAlign=top><TD colSpan=2></TD><TD width="30%" colSpan=2>Xylene</TD><TD>1330-20-7</TD><TD>10-30 %</TD><TD></TD><TD colSpan=2></TD></TR><TR vAlign=top><TD colSpan=2></TD><TD width="30%" colSpan=2>Solvent Naphtha (Petroleum), Light Aromatic



</TD><TD>64742-95-6</TD><TD>10-30 %</TD></TR></TBODY></TABLE>
... I assume the zinc must be in the "ingredients determined not to be hazardous".

But as Lou says ... "play it safe" - always wear a suitable mask when spraying any sort of paint.

Heres what our metalwork teacher gets us to read in regards to the dangers of Zinc

http://www.anvilfire.com/iForge/tutor/safety3/index.htm

REgards Lou

That's a bit of a read and a rather sad story - but it's high in emotion, and somewhat low in verified facts.

Yes this guy died from pneumonia and it was most likely brought on by the massive dose of thick white zinc oxide smoke.

It states that he got over the chemical effects of zinc oxide (what is dubbed "metal fume fever") within a couple of days.

It was his emphysema compromised lungs that couldn't handle the physical effects of the massive fume intake. But this guy also could have just as easily got pneumonia from a severe exposure to wood dust or any other dust or heavy smoke/fume.

I think the bottom lines is that zinc oxide does NOT accumulate in the body and by all the factual evidence that I've found, it does not have any known long term effects.

BUT (there's always a but) if I was doing anything that generated any significant amount of fumes or dust (of any kind) I would take the appropriate precautions.

Dear Everyone So Far...

Fantastic Forum, this place. Just so helpful...

Lou and Vernon, I hadn't actually thought about using a mask up there, but now that you have raised the issue, as luck would have it just a couple of weeks ago I was at Amazing Paints (the guys over at the Virginia store are really good to deal with) and I clocked up a bit of credit when I exchanged something for the next one down. Since the fellow there was so understanding about the return, I spent the credit there-and-then on (wouldn't you know!) a couple of chemical filter cartridges for my dust mask. I only had the particle filter cartridges before that! So I'm "In Business" on the safety front...

Durwood, your reply is solid (as per usual I am noticing for most of your replies in the threads you participate in...:2tsup: You know so much about "stuff", that your head must hurt.) The suggestions about Turps instead of Acrylic Thinners is well worth a try, since it will assist the Gal to soak-in better, and probably cause me less problems at the nozzle to boot. Likewise, the marbles are a great idea. Pity that my Paint Bowl (an underneath suction-type) is made of just thin-ish aluminium that feels like it wants to dent easily (maybe I can find some of those mini "Cat's Eyes" marbles up in the cupboard...). Also, there's definitely no air-pressure feed going down into the Bowl either, so it looks like I'm in for some fun...:doh:

Does anyone know of any good websites that explain the interplay between the Air Flow Control and the Paint Flow Control in a fairly basic way (ie. Spray Gun Theory for Dummies :B) Don't go searching for me or anything - just if you happen to know of one offhand.

Thanks again,
Batpig.

Thats the way M8 All i am trying to get to u is be safe n if u choose not to thats ur choice................... Just to be aware of the potential risks!

I have a beautiful daughter n a loving family a goddess of a partner and will not put myself at risk................ I want every day i can leech from this realm to spend with them so wont compromise!..........bottom line get that mask on!

As said good luck with the job n mask up!.....................................Ur worth it! n Im sure ur loved ones think so too!

Theres nothing better than pulling off a Great job knowing u've done it safely n havent cut corners!

Regards Lou:2tsup:

Why anyone would think this noxious stuff isn't dangerous has got me beat heres the hottest mail on zinc oxide straight from the material data sheet:

http://www.jtbaker.com/msds/englishhtml/Z3705.htm

Great thing is is take the proper precautions n you'll be fine - Thats the great thing bout material safety data sheets they tell us the risks n how to manage them.................

We recently had a speaker in a trade school thats been a boiler maker for 40 years telling us that GAL is dangerous n that its an accumulative poison (Meaning the more ur exposed to it the more it builds up in the body)

This bloke said to us (I was there at the presentation) that once this "????" builds up enough in ur body it starts ripping ur liver apart n is extremely hard to get rid OF!!!!

Kit up boys dont take the risk!.......................

U make ur own minds up on what this means!!!!! N if interested do a google search theres pleanty of evidence suggesting Zinc is bad ????!

At the end of the day as with all these things why take the risk........................... besides who u gonna believe the manufacturer shouting how safe there product is or the workers who have been workin with the ???? for 20 yrs

I'm kittin up!

Regards lou:2tsup:

Controls on a spray gun are fairly simple!

If the gun is a suction feed ( pot underneath and a hole in the top of the lid) then you will need about 40 to 60 psi to make it work ( only use enough to make the gun work properly) . The compressed air sucks up the paint in the pot as it causes a vacuum at the tip of the gun. You need a hole in the top of the pot to let air into the pot to push on the paint so it can be sucked up the tube.

If the gun stops working 90% of th time its that the tip where the needle is, is dirty. If the gun coughs and splutters it is either out of paint or the hole is blocked up in the lid. Or the paint is too thick -most of the time.

How to spray?

If its a reasonable engineered gun it will have a fan control- this is a knob you turn in and out which restricts the flow of air to the side horns on the air cap. Turn it out full and the air is allowed to come out of the horns on the side of the air cap. This will squash the round stream of paint into a flat fan. Usually if yoy are spraying a big surface a wide fan allows you to paint a bigger area. If you turn it down all the paint is put into a smaller area so its thicker and will be more likely to cause runs.

The material adjustment behind the needle allows you to control how much paint comes out of the gun. Turn it in reduces the flow, turn it out increases the flow. You determine the way you want to spray ( how far away you hold the gun and how fast you move it along the surface. By adjusting the material flow you can control the amount of paint put down onto the surface as you move along.

You need to be able to see how the paint is going on. So you want to be moving at a slow pace so you are in control. The faster you move along the more paint you have to have to wet the surface the slower you move the more you have to cut the amount back so that it doesn't flood the surface and cause runs.

Keep the gun at right angles to the surface and the same distance away and keep the speed you move the gun along the same. Don't twist you wrist as this will make the distance greater.

Lou - I'm hearing ya'. I'm right into those "cumulative" damage things, like Hearing Damage (Always wear Earmuffs with tools, and don't fall asleep with the Headphones on!:no:) and Skin Damage (I wear long sleeves, trousers, and gloves when I mow, even if it's the middle of Summer, and even then I prefer to mow in the blazing heat of the middle of the day because the Sun has less of a chance of getting past the brim of the hat onto your face or neck:wink:. Crazy, hey! I must be part-English...)

Durwood - another solid effort. I didn't realise until your post that the Air Flow Control was simply a "Splitter" of sorts that alters the ratio by which air is split between the Nozzle and the Horns. Chinglish instructions neglected to mention this ("Surprise, Surprise..." and a Gomer Pyle smiley if there is such a thing - Hang on, this must be it: :D) Anyway, I had a bit of a practice out in the backyard this arvo with some Acrylic and cardboard, and you were dead on. Air Flow Control all the way in equals Spot Spray plus more pressure behind spray. Air Flow Control out equals Fan, but with less pressure due to air being diverted to Horns. Therefore increase pressure at Regulator if Fanning. Will probably Fan, especially if thinning with Turps since not as much instant flash-off as with Premium Thinners. As regards Paint Flow Control, will have to play it by ear - all the way out might help get the gunk up and out of the Bowl, but at the expense of good Atomisation I would guess.

Will now bide my time until an appropriately overcast but non-rainy day rolls around to put pristine theory into disastrous practice...

Thanks all,
Batpig.

Well, the job is done now...

For the purpose of future reference for anyone wanting to do the same thing for the same reason, I will mention the following observations:

I first tried pre-treating the rusty spots with a Septone product called "Rust Prime" because it was supposed to dry black, instead of normal Rust Converter which leaves a white residue. To my mind, the danger with using normal Rust Converter for little bits here and there up on a roof is that only the rust goes white, and only then if you truly saturate the rust with it. Otherwise, the Rust Converter dries more or less clear, and is therefore pretty hard to spot when you come back on the next overcast day with the Cold Gal. Now, methinks that if a patch of slightly-spotty but mostly-decent roof sheeting was coated with Rust Converter and subsequently not hit with the Cold Gal, you've probably just ended up mostly ruining whatever remained of the galvanising protection in that patch - ie. a bigger, rustier patch will probably show up there in the future...

So I tried some Rust Prime because I thought it would dry black (which would really stand out on the grey roof), but no-siree - only the rust goes black. The rest dries virtually clear like normal Rust Converter. Therefore just as tricky to use on a roof as normal Rust Converter. So I didn't end up doing any rust converting at all. Am relying instead on the soaking-in ability of Cold Gal thinned with slower-drying Turps, applied on an overcast day. Only time will tell whether there is any substance to my theory...

Regarding the application of the Cold Gal, it took two goes to do because the first 500ml can (Septone brand from Supercheap) was the largest they had (cost about $34) but still didn't get me very far in the way of coverage. Seemed pretty thick, though. Probably really good stuff for touching up welds, etc, but presented an ongoing problem with solids clogging up the nozzle. This could have been my fault due to not using enough thinner, and also knocking some of the already-dried solids off the edge of the can back into the mix when I was stirring it. Also, I used Turps to thin it, when the specified thinner is General Purpose Thinners, so these solids wouldn't have stood much of a chance of being dissolved again.

The second attempt was after buying a can of White Knight brand Cold Gal from Bunnings (1L for about $48). Seemed a bit thinner from the start. Can seemed fresher too, with not much noticeable sediment sitting on the bottom, which was in contrast to the can of Septone from Supercheap. (Mind you, that might just mean that there is a Sheet-Load more Zinc in the Septone product, which again might mean that it totally Rocks for weld touch-up work with a brush.) Interestingly, the specified thinner for the White Knight version was Turps, which suited me to a Tee...

Probably needed to use a slightly bigger nozzle than the 1.5mm that was used (thing started to clog-up on and off after a half-hour long chin-wag with a neighbour :B). In general, spraying was a better method than aborted first effort with a brush, but is actually a two-man job because you need a second guy to stop the air-hose from scraping off the freshly applied Cold Gal from the top of the ribs you've just painted as you move around. Bro did the honours in this department. Somehow don't think spraying is the full answer to the problem, though. Used a hell of a lot of air! 2.5hp, 50l Compressor must have kicked in about twenty times just spraying about 1.5L of Cold Gal, and was very hot by the end, to the point where I am now wondering whether a crappy Spray Gun (a'la mine :D) might actually use more air than a decent Gun to do any given job.

Clean-up of the Gun with full Thinners was a revelation! Is there any way of recovering the stuff when doing this so that you can use it again for cleaning in the future after settling out the solids? Tried spraying it into a bottle - just ended up with it spraying back out again all over my hands and face...

In hindsight, perhaps a small roller would have been the best applicator, but keeping the tray upright and moving it around on the ribs would have been next to impossible, and solvent evaporation up there in the heat and wind would have been a major factor (and probably the strongest Pro in favour of the Spray Gun). If I ever do this sort of thing again, I will be looking very extensively into whether you can get one of those bottle-fed roller setups with just a small roller on it, and maybe a short hose between the roller and a bottle hanging by a shoulder strap. Then will just have to see whether the Cold Gal will be able to come through the roller cover...

Best Wishes,
Batpig.

Hi BP,

I hope the cold gal you used says it can be sprayed. Some types can't be sprayed becuase the particle size isnt small enough. You'll know becuase when you come to clean the gun out there will be a thick clay like residue left. When the pot is pressurized the size graded particles get pushed out of suspension. True Cold Gal contains 3 different sizes of particles that form 2 layers of zinc upon drying. the two larger size particles settle to the bottom of the paint layer and the fine particles chemically lock on the outer surface of the coat.

Anyway bit late now - and you've already learnt spraying cold gal is troublesome .

Dear Doogie,

That's pretty esoteric stuff - you must be some sort of "Cold Gal Guru..."
There wasn't any settlement to speak of on the bottom of the pot (Thank Heavens by the sound of it!) on either occasion. The White Knight can said it could be sprayed (and it was the least thick of the two), but I don't think the Septone specifically mentioned this ability (definitely no sludge left behind, though).

Another brother turned up this arvo and said that he had been talking to a particularly fussy Tradie up his way (Nambour) about the situation, and this fellow apparently said that the best thing he's ever come across for arresting corrosion on roofs is Penetrol. I've just had a look at their website, and there's one or two particular products they do which seem to be aimed specifically at corrosion. Their Corrosion Inhibiting Primer dries a Red/Orange colour. Would therefore be easy to pick out on a galvanised roof if you were following it up with Cold Gal.

All the Best,
Batpig.

HI BP

- lol yeh I'm into truly eosteric stuff - like paint technology, adhesives, rare plaster formulations and cultural psychology (dont ask)!

Penetrol is truly excellent stuff and should be in every renovators paint stash. It seals and stops rust, it waterproofs gyprock topping, it seals stone and concrete permanently, and can be used to prime smooth sanded timber with no brush tip marks.

sounds like the cold gal went ok for you then - thats good!