Sparying Model air using HP-BH
- Thread starter slupanter
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G
I have never found the need to thin Model Air but I do know that some do to around 25%thinners to 75% Model Air. This would be quite thin though.
Now you say it just stops spraying, which would suggest that it starts to spray then stops. Correct?
Model air should be fine out of the bottle, but I know there are some that thin it down more.
How is your air presure? I'm a bit in the dark as to what HP-BH is for a fish so specific help is hard to give. However a few things to try:
Can is spray with out stopping if you spray water (distiled) through it?
The air presure could be to low, and not being able to push the paint through the nozzle.
Does the paint in the cup or glass start to bubble; thats a sign of a blockage.
This was a problem I had a bit when I went over to Vallejo acrilics. turning the air up helped almost imediatly. Remember that the thicker the paint the more air you will need to push it through the air brush. Contra for fine work with better control, you will need to screw right down for the air and thin the paint enough to get it through the airbrush.
As I learned through the forum the best way to figure it out is to choose your paint and play with it. That way you get to know both the paint and the air brush. How much the paint need sto be thinned or how much air pressure you will need to get the result.
Hope thats some help.
Ian M
Model air should be fine out of the bottle, but I know there are some that thin it down more.
How is your air presure? I'm a bit in the dark as to what HP-BH is for a fish so specific help is hard to give. However a few things to try:
Can is spray with out stopping if you spray water (distiled) through it?
The air presure could be to low, and not being able to push the paint through the nozzle.
Does the paint in the cup or glass start to bubble; thats a sign of a blockage.
This was a problem I had a bit when I went over to Vallejo acrilics. turning the air up helped almost imediatly. Remember that the thicker the paint the more air you will need to push it through the air brush. Contra for fine work with better control, you will need to screw right down for the air and thin the paint enough to get it through the airbrush.
As I learned through the forum the best way to figure it out is to choose your paint and play with it. That way you get to know both the paint and the air brush. How much the paint need sto be thinned or how much air pressure you will need to get the result.
Hope thats some help.
Ian M
this is the brush; https://airbrushes.com/popup_image.php?pID=32ℑ=0&osCsid=fcc081467c37730b90a5c633f67574bb\ said:
i use 29psi because i was told that any higher would damage the brush. is this true? it sparys water, thinner and paint when the air valve on the brush is pulled full (max air power)
29psi is too high, try 15-20psi, Iwata work better at lower pressures
Low viscosity paint like model air will generally require less pressure, also paint will dry very quickly so if you stop spraying even for a short period of time it could clog, when you are cleaning your AB do you blow reamer or other cleaner backwards through your nozzle? you could be getting a build up in there.
G
Hi,\ said:
The Pre-Set Adjuster Screw (little nut at the back) is to set the amount of needle travel for greater control of the amount of paint released from the nozzle.
I can assure you that you will not damage the airbrush using it at high pressures. An Iwata airbrush is manufactured to the Highest Standards using High Quality Materials. I sometimes use 1 of the 7 Iwata Models I have at 4 bar which drops to 3 bar once running, and have never had any problems.
The reason your airbrush is stopping is due to a build up of paint residue inside the nozzle. There can be a build up even though the needle is visable at the end of the nozzle. The reason the paint is spraying and then stopping is due to the following:- (To explain the needle positions, 0-10 zero is off and 10 is Full) When the needle is forward in the nozzle (0) and showing through the needle cap it has formed a hole through a blob of paint residue and the residue is building up around the needle. Then when you pull back on the Main Lever (Trigger) to say (5) the needle allows some paint to flow, but as you pull back further to say (10) the needle will be back enough to allow the residue to be blown forward, thus covering the hole that the needle normally sits in. The residue is something like a flap of paint and when you set the trigger forward to (0) the needle pushes through the build up and the next time you pull the trigger back the same happens again, but the next time the residue gets thicker and thicker until it gets to the point when no piant will be sprayed at all, as the needle will not return to (0). If you remove the Pre-Set handle at the back of the airbrush and undo the Needle Chucking Nut and withdraw the needle slightly, and then push it forward again, you will feel a "spounginess" as you push the needle forward. (Don't force the needle forward as you may dammage the tip of the nozzle).
The way to clear the residue that has built up is to remove the nozzle and using the plastic tube that comes with an aerosol of Liquid Reamer or IPA 170 and open out the end of the tube enough to allow you to put the tip of the nozzle into the end of the tube. Then whilst covering the nozzle with a paper towel or cloth to catch the paint residue, press the aerosol a few times until the cleaner and pressure forces the residue out. (Do not poke anything into the back of the nozzle, as you may damage the nozzle or push the blockage further in to the nozzle.
I hope this helps.
Regards,
Leslie.
RailwayModels4U
G
What size nozzle are you using?
G
Who are you asking the question of?\ said:
If you are asking what size nozzle the HP-BH has a 0.2mm fitted as standard, but can be upgraded to a 0.3mm.
Regards,
Leslie.
Leslie that is a most comprehensive answer! You have most eloquently explained his problem. I can suggest a means of minimising the chances of such blockages occurring. I spray mainly Xtracrylix which are particularly prone to drying in the nozzle!
I would suggest adding a drop or two of an acrylic retarder to your paint cup. I notice that you are in Solihull,if you can't find an artists supply store there a quick trip into Birmingham will enable you to visit an artists supply shop called Spectrum. It is in the under passage (Fletcher's Walk) by the town hall at Paradise Circus. They do the Liquitex range which work for me, they are also very friendly and helpful. These shops can be a goldmine for modellers so leave your credit card at home LOL!
Also, as someone else has said, there is no substitute for a bit of experimentation. You will find what works for you and wonder what all the fuss was about.
Cheers
Steve
I would suggest adding a drop or two of an acrylic retarder to your paint cup. I notice that you are in Solihull,if you can't find an artists supply store there a quick trip into Birmingham will enable you to visit an artists supply shop called Spectrum. It is in the under passage (Fletcher's Walk) by the town hall at Paradise Circus. They do the Liquitex range which work for me, they are also very friendly and helpful. These shops can be a goldmine for modellers so leave your credit card at home LOL!
Also, as someone else has said, there is no substitute for a bit of experimentation. You will find what works for you and wonder what all the fuss was about.
Cheers
Steve
G
Hi Alexander,\ said:
The nut under the Colour Cup is the MAC Valve. This screw is used to micro adjust the air pressure in front of the the paint channel, which can be used on Full or adjusted down to a wispher for special effects like stippling etc, or when you want to get in close to the model and spray an area like the size of a pin head etc.
I don't have the HP-BH but I have the Hi-Line HP-CH which is in the same range as the HP-BH, but the CH has a larger Colour Cup and the standard nozzle size is 0.3mm wheras your HP-BH is fitted with a 0.2mm nozzle as standard, but can be fitted with a 0.3mm. My CH can be fitted with a 0.2mm and I have both nozzles sizes. If you change the size of your existing nozzle for the optional size, you need to buy the 0.3mm nozzle + 0.3mm nozzle cap + 0.3mm Needle Cap, but you don't need to buy a 0.3mm needle as the 0.2mm needle will work with the 0.2mm parts, I assure you. The HP-CH has a 0.3mm needle and to convert the CH to a 0.2mm one needs to buy the 0.2mm nozzle + 0.2mm nozzle cap + 0.2mm needle cap, but the 0.3mm needle does not need to be changed. Strange I know how this sounds, but it is correct information I am giving you, as I have these parts and use them daily.
I hope this helps.
You can also PM me if there is something very technical that you are not sure of and I will help you.
Regards,
Leslie.
RailwayModels4U
I would also buy some super lube to protect your air brush, I'm out of stock until about Wednesday but you can find it here
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