Spray finishing

[Stormer1940]

I am looking at partitioning off a 40ft container we have arriving tomorrow and using part of it for spraying. At the moment I only have a cheap spray gun that came from machinemart but i suppose this will get me going to start with. Can anyone suggest a better gun to purchase further down the line? I have a 18cfm belt driven compressor and have a water trap fitted between the compressor and airline already. Any other tips would be greatly appreciated. I would only be looking to use water based at this time.

 

[MikeJhn]

As you have a compressor already, I would get a HVLP convertor gun, less overspray therefore less need for expensive filtration and uses less material, therefore cheaper in the long run and a better system, ultimately though IMO an HVLP system would be even better.

I went down this route a few years back and this is a link to my investigations: hvlp-investigation-and-review-t97520.html

Mike

 

[Stormer1940]

As you have a compressor already, I would get a HVLP convertor gun, less overspray therefore less need for expensive filtration and uses less material, therefore cheaper in the long run and a better system, ultimately though IMO an HVLP system would be even better.

I went down this route a few years back and this is a link to my investigations: hvlp-investigation-and-review-t97520.html

Mike

Thanks Mike I'll take a look.

 

[No skills]

I'd suggest you get a powerful extractor fan if your doing that in a container.

 

[MARK.B.]

I'd suggest you get a powerful extractor fan if your doing that in a container.

+1 to that =D>

 

[MikeJhn]

A plate axial fan will do, something like this: http://www.justfans.co.uk/soler-palau-h ... p-357.html but where it exhausts too is important, so location inside the container could be compromised accordingly, I would suggest spraying at the far end of the container so that any airborne paint does not have to pass anything else inside the space, this would obviously give you only three options for location of your extract, ideally its best to spray towards your extract point.

Mike

 

[Stormer1940]

A plate axial fan will do, something like this: http://www.justfans.co.uk/soler-palau-h ... p-357.html but where it exhausts too is important, so location inside the container could be compromised accordingly, I would suggest spraying at the far end of the container so that any airborne paint does not have to pass anything else inside the space, this would obviously give you only three options for location of your extract, ideally its best to spray towards your extract point.

Mike

Far end of container will be made into storage and then I plan to partition half off and build a access point with 2 doors that would swing back into the non storage area when I need access to storage area. I'm obviously going to have to vent the container up to allow air circulation. Thanks for link to extractor fan that gives me a target point to aim at.

 

[MikeJhn]

I spray in a lean to type structure, which is mostly open to atmosphere, with the HVLP system there is so little overspray this is possible without any type of extract, 90% of the paint going onto what I am spraying, it works perfectly, so thinking laterally some kind of pop up structure outside the container may be an answer, although that would make it weather dependant.

One other thing if you go the HVLP router get a non bleed gun, guns that allow air to escape prior to pulling the trigger are an absolute pain, kicking up dust which inevitably ends up on your work.

Mike

 

[n0legs]

If you do go with an extractor fan put it down low. Then get your 'make up' air vent, definitely with a filter, up high,
Clean in, dirty out.

 

[Stormer1940]

Thanks all. Mike have you got a hvlp convertor gun which you could link to ?

 

[MikeJhn]

You have just changed your post to say conversion gun, it previously said system, however here is my post to answer you previous unedited post.

No I don't have a link to a conversion gun, see my second paragraph below.

The system I particularly like is the Fuji HVLP http://www.axminster.co.uk/search/?q=Fuji&nR[visibility_search][=][0]=1& but I am biased as I have a Q4 which is a four stage unit, the minimum I would recommend if you are going to spray latex or anything with a high solids content is a three stage unit, my four stage unit will spray High Build Primer without dilution, one of the guys on here had an Appolo three stage unit in the for sale section recently.

On the HPLV compressor conversion guns, I am not convinced they actually work well enough, I know I am going to regret that comment, the ones I have used do not come up to the standards easily achievable with a Turbine HVLP unit, when I carried out my investigations into spraying I quickly dismissed them as they could not do what I wanted, I would suggest you hire in a conversion gun and then hire in a Turbine HVLP spay system and make up your own mind.

Mike

 

[Stormer1940]

You have just changed your post to say conversion gun, it previously said system, however here is my post to answer you previous unedited post.

No I don't have a link to a conversion gun, see my second paragraph below.

The system I particularly like is the Fuji HVLP http://www.axminster.co.uk/search/?q=Fuji&nR[visibility_search][=][0]=1& but I am biased as I have a Q4 which is a four stage unit, the minimum I would recommend if you are going to spray latex or anything with a high solids content is a three stage unit, my four stage unit will spray High Build Primer without dilution, one of the guys on here had an Appolo three stage unit in the for sale section recently.

On the HPLV compressor conversion guns, I am not convinced they actually work well enough, I know I am going to regret that comment, the ones I have used do not come up to the standards easily achievable with a Turbine HVLP unit, when I carried out my investigations into spraying I quickly dismissed them as they could not do what I wanted, I would suggest you hire in a conversion gun and then hire in a Turbine HVLP spay system and make up your own mind.

Mike

Sorry prob me getting confused with conversion and convector, I wrongly assumed you had made a typo :shock: Escuse my ignorance but I assume you run air line into the box or am I way off or is this a entirely independent system?

 

[MikeJhn]

True HVLP does not use a compressor, the box on a HVLP system is a stand alone unit and has a number of fans/turbines inside it, basically a vacuum cleaner fan in reverse, each fan is a stage of the turbine the more fans the more stages, the more air it can supply to the gun, hence "High Volume Low Pressure" its a different system to that usually used with a compressor which is a "High Pressure Low Volume" system, because of the advantages of the HVLP system manufacturers have tried to come up with a gun to use with a compressor which uses the HVLP system of spraying, this is called a conversion gun.

Additional advantages of HVLP are many, a few are, portability, paint is warmed by the air volume in the gun, this is said to be a disadvantage in warm weather, but I have not found that to be the case, by warming the paint there is less chance of runs, the lack of bounce back cannot be over emphasised, the controllability of the spray pattern and paint volume at the gun and more:

Mike

 

[n0legs]

I've heard good things about one of the Sealey guns.
One of the lads with my BIL uses a Sealey 741 for guide and light primer coats. Cheapish at around £40-50.



Edit to add.
I actually just checked it out, I asked him by text a little earlier. It's model number HVLP 741 and can be had from various places from £25 upwards. In my checking I found the HVLP 742 (2.0mm needle) which again can be bought around the £25 mark. Both seem to have quite a demand though 15cfm is quoted on the Sealey site.

 

[n0legs]

Question for Mike.
In your research did you come across or test the Apollo 7500GT HVLP gun? Opinions?

 

[MikeJhn]

I have not tried or investigated either of these guns, but on observation the Sealey 741 is an all metal gun, I have used an all metal gun and they become uncomfortably hot during use with a turbine which severely restricts the amount of spraying time available in any one session.

As to the Appollo 7500GT it looks as though it does not have a non return valve on the pressure pipe and therefore if used at any angle other than upright will cause paint to contaminate the pressure side of the gun and cause spitting of the paint delivery unless there is some other clever valve that prevents this, the teflon coated cup from Appollo is known to flake when used with solvent based paints, it looks like a very cheap clone of the SES gun.

This is a much more acceptable HVLP gun at under half the cost: http://www.sprayequipment.co.uk/hvlp-tu ... y-gun.html

Mike

 

[n0legs]

Interesting Mike, very interesting.
So are you a fan of the old school suction type gun over the gravity guns?
Seems odd to me a manufacture makes a gravity gun that could self contaminate it's internals. First time I've ever heard of it in a gravity gun to be honest.







Apollo Sprayers International, Inc. celebrate a giant leap forward in TrueHVLP technology with the Apollo7500T, The AtomiZer. This unique spray gun delivers enhanced True HVLP performance and flawless results with any make turbine or air compressor, 3HP/20 gallon (75 litre)tank or larger. Seeing is believing with this breakthroughtechnology:

I've been saying for months that the criteria for a HVLP system lies with the spray gun and not how it's method of propulsion is created, maybe now I'll be believed.

Original here:-
http://www.hvlp.com/product/a7500t-seri ... spray-gun/

 

[MikeJhn]

Its not so odd that manufactures make a gun that can contaminate itself, it happens if the gun is used incorrectly at an angle and the paint gets to the underside of the lid, HVLP guns are pressurised above the paint by the tube that goes to the top of the paint container, irrespective if its gravity or suction (conventional description) that's why the non return valve is important, for the suction type of gun a baffle is also available to delay the paint getting to the pressure port when tilted, when using these guns its handy to know that turning the paint pot on the gun can delay this when using it at an angle.

I don't use a so called gravity gun as I feel it makes it top heavy and the pot is too small for any meaningful use, in fact most of the time I use a remote paint pot on the floor.

Mike

 

[MikeJhn]

By demand from suppliers Fuji re-introduced a moveable side fed gravity pot: http://www.axminster.co.uk/fuji-g-xpc-g ... gun-211962 to enable unconventional angles to be used with this type of gun.

You can get all the information you need on HVLP guns here: http://www.fujispray.com/hvlp-spray-guns/

Mike

 

[sometimewoodworker]

I am looking at partitioning off a 40ft container we have arriving tomorrow and using part of it for spraying. At the moment I only have a cheap spray gun that came from machinemart but i suppose this will get me going to start with. Can anyone suggest a better gun to purchase further down the line? I have a 18cfm belt driven compressor and have a water trap fitted between the compressor and airline already. Any other tips would be greatly appreciated. I would only be looking to use water based at this time.

On my setup I have two particulate filters on the air line. The first is about a 5 micron and has a clear plastic body the second is a .5 or 1 micron in a metal case these both have drain plugs in the bottom and are about 3 meters from each other, the first gets a little water occasionally the second has always been dry.

I also have a pressure control at the compressor, one at the wall outlet and one on the gun. My nice spray gun was around $400 and is a HVLP conversion gun from a compressor similar to yours. I have a few cheap guns that have worked well, but the expensive one is much nicer to use.

The next thing I want is a large secondary tank to reduce cycling of the pump, and I'm going to repurpose either an old LPG or gas cylinder for that.

I've sprayed water based, thinner based and alcohol (shellac) with the gun and it's been great. As we have new house being built I'm going to have a try with latex next.


I'm now getting a purpose built room built for finishing so SWMBO will be happy, I hope, to have the smell reduced.