Pressure

[67flh]

Air pressure questions. The manual for my gun says 2.5-3.5 bar which equals 36-50#'s Is that the rated pressure to the gun or for the gun? The primer info states 8-10 psi at the cap and 29-40 psi at the gun. For the life of me I cannot grasp what that means. In going over the threads I gather that my regulated pressure to the gun should be 60 to 80 psi. I have a regulator and can easily set that, what is the pressure I set at the gun?

[Ronf]

Air pressure questions. The manual for my gun says 2.5-3.5 bar which equals 36-50#'s Is that the rated pressure to the gun or for the gun? The primer info states 8-10 psi at the cap and 29-40 psi at the gun. For the life of me I cannot grasp what that means. In going over the threads I gather that my regulated pressure to the gun should be 60 to 80 psi. I have a regulator and can easily set that, what is the pressure I set at the gun?

To get 8-10 psi cap pressure you need the inlet pressure to be 36-50 psi depending on gun. That inlet pressure is set with the trigger pulled, not static pressure. Many guns have a halfway pull that allows you to set inlet pressure without dispensing product

[67flh]

To get 8-10 psi cap pressure you need the inlet pressure to be 36-50 psi depending on gun. That inlet pressure is set with the trigger pulled, not static pressure. Many guns have a halfway pull that allows you to set inlet pressure without dispensing product

So I should take that set the little regulator that is attached to the gun, by pulling the trigger half open and adjust the pressure accordingly? Then test it with paint to see how it is?

[Len]

So I should take that set the little regulator that is attached to the gun, by pulling the trigger half open and adjust the pressure accordingly? Then test it with paint to see how it is?

Paint or no paint shouldn't make any difference in the needed inlet pressure. If I want an accurate pressure I assemble the gun with the inlet pressure gauge, attach the air hose and pull the trigger then adjust the inlet pressure to the desired PSI.

[Phil V]

Air pressure questions. The manual for my gun says 2.5-3.5 bar which equals 36-50#'s Is that the rated pressure to the gun or for the gun? The primer info states 8-10 psi at the cap and 29-40 psi at the gun. For the life of me I cannot grasp what that means. In going over the threads I gather that my regulated pressure to the gun should be 60 to 80 psi. I have a regulator and can easily set that, what is the pressure I set at the gun?

36-50#'s means 36 to 50 pounds per square inch commonly called PSI. 8 to 10 psi at the cap is a number 99.9999% of painters can ignore, because it takes a special tool connected to the air outlet of gun to read 8 to 10 psi at the cap. You can ignore the primer info of 29 - 40 PSI at the gun because the primer company has no idea what gun you're using. (which can vary widely depending on the gun).

Sounds like you are obviously using an HVLP gun so set your air pressure at the gun with the trigger pulled to 30 psi and see how the gun handles the paint (or primer) you're spraying. Not all paint has the same viscosity (thickness or thinness) so the air pressure at the gun will have to be fine tuned to the material you are spraying. If the air pressure is too low then the material will go on with serious orange peel. If the air pressure is too high then the material will go on dry. Both conditions can cause dry spots AND runs. Usually when putting the paint on too dry the painter tends to spray more material on the panels trying to the get the paint to flow out, that in turn causes runs. You as the painter have the joy of finding the "sweet spot" of where the paint goes on smooth and flows out to a mirror like finish. Your paint application technique is just as important as setting up the gun to deliver the paint correctly.

[67flh]

[QUOTE=Sounds like you are obviously using an HVLP gun so set your air pressure at the gun with the trigger pulled to 30 psi and see how the gun handles the paint (or primer) you're spraying. Not all paint has the same viscosity (thickness or thinness) so the air pressure at the gun will have to be fine tuned to the material you are spraying. If the air pressure is too low then the material will go on with serious orange peel. If the air pressure is too high then the material will go on dry. Both conditions can cause dry spots AND runs. Usually when putting the paint on too dry the painter tends to spray more material on the panels trying to the get the paint to flow out, that in turn causes runs. You as the painter have the joy of finding the "sweet spot" of where the paint goes on smooth and flows out to a mirror like finish. Your paint application technique is just as important as setting up the gun to deliver the paint correctly.[/QUOTE]

Yes am using a HVLP gun and for the first time. Great replies! It has been 20 years since I painted with a siphon gun so I am looking forward to this. I have a small utility trailer that is going to be my practice piece. I have lots of paint and plenty of time to get it right. Thank you all for the replies.

[Phil V]

Yes am using a HVLP gun and for the first time. Great replies! It has been 20 years since I painted with a siphon gun so I am looking forward to this. I have a small utility trailer that is going to be my practice piece. I have lots of paint and plenty of time to get it right. Thank you all for the replies.

What type of paint do you plan on spraying ? (brand would help also).

[67flh]

What type of paint do you plan on spraying ? (brand would help also).

Shop-line JP37x Epoxy primer Case IH Iron Gard Enamel made by Valspar with Shop-line JH6002/PT hardener

[Phil V]

Shop-line JP37x Epoxy primer Case IH Iron Gard Enamel made by Valspar with Shop-line JH6002/PT hardener

Am I correct in assuming the Case IH Iron Gard Enamel is synthetic enamel as opposed to acrylic enamel ?

Either way you should be using the same brand hardener as the enamel. Not good to mix different brands of hardeners.

Shopline epoxy primer is decent primer. Takes a long time to cure/harden.

[Ronf]

So I should take that set the little regulator that is attached to the gun, by pulling the trigger half open and adjust the pressure accordingly? Then test it with paint to see how it is?

Yes, but there are many factors that have to be taken into consideration beside setting pressure, i.e. tip size, setting fluid flow (I run most of my guns wide open and then 1/2-1 turn in depending on product and reduction), viscosity of fluid, paint reduction, distance to panel application, hand speed, etc.
My advice is before you start learn to set up gun and check for proper pattern on a practice panel.

[67flh]

Am I correct in assuming the Case IH Iron Gard Enamel is synthetic enamel as opposed to acrylic enamel ?

Either way you should be using the same brand hardener as the enamel. Not good to mix different brands of hardeners.

Shopline epoxy primer is decent primer. Takes a long time to cure/harden.

Trying to locate answer as to what type of enamel it is. As far as using the same brand of hardener goes I am on 4 different message boards regarding garden tractors and all one would ever need to know about them. What I gather is any hardener will work in this paint, the answers are all over the place. Using Shop line with the IH paint was recommended by several restorers. The PPG guy told me to mix some up shoot it and see how it works, he said I would have no problem recognizing an issue. I appreciate your responses!

[67flh]

Yes, but there are many factors that have to be taken into consideration beside setting pressure, i.e. tip size, setting fluid flow (I run most of my guns wide open and then 1/2-1 turn in depending on product and reduction), viscosity of fluid, paint reduction, distance to panel application, hand speed, etc.
My advice is before you start learn to set up gun and check for proper pattern on a practice panel.

I will be doing some practicing a lot of practicing before I actually shoot my tractor. I have lots of color on hand and a big trailer with lots of flat surface to learn on. I will work with it till I am convinced that I am good to go. Thanks for your response.

[Len]

I will be doing some practicing a lot of practicing before I actually shoot my tractor. I have lots of color on hand and a big trailer with lots of flat surface to learn on. I will work with it till I am convinced that I am good to go. Thanks for your response.

I've said this several times on this forum, I think the two most important things that help spray painting is HEIGHT AND LIGHT. Get the vehicle (or whatever) up so that you're not crawling around while spraying and have good lighting coming from behind and overhead if possible. Watching the reflection in the wet paint can help get it right by showing you if it's too wet or too dry during the application.

[MidnightOilJK]

Yes, but there are many factors that have to be taken into consideration beside setting pressure, i.e. tip size, setting fluid flow (I run most of my guns wide open and then 1/2-1 turn in depending on product and reduction), viscosity of fluid, paint reduction, distance to panel application, hand speed, etc.
My advice is before you start learn to set up gun and check for proper pattern on a practice panel.

He is correct,

Temperature, Reducer selection, tip size, viscosity, high flow fittings, etc etc will all effect what you need to do on your end.

[Phil V]

I cringe every time someone says turn this knob in 2 turns and that knob in 1 turn. Every gun is different. There are NO settings that apply equally to all guns as far as fan width is concerned. As far as the fluid control knob -- open it wide open (so the trigger pulls all the way back)and leave it there for as long as you own the gun. You want to control the amount of fluid going through the gun ? Thats what your trigger finger is for. Pull the trigger back as far as you need it, and in most cases the trigger is pulled all the way back. The only time the trigger isn't pulled all the way back is when you're using a full size gun to paint something small. In which case you dial back the air pressure, narrow the fan a little and don't pull the trigger all the way back.