Spray systems

[maxmotoring]

Wondering what is the best equipment for paint spraying traditional nitrate and butyrate dopes.
Has anyone any experience or recommendations whether HVLP systems using a turbine or conventional compressor spraying being better. Gravity fed or siphon? Comments welcome.
Thank you, David

[mike newall]

Depends whether you have a compressor..

If in the workshop, a Spiegen HVLP gravity gun will cost under £40. An excellent gun, easy to use and clean. Very little overspray.

If in the field, use an electric HVLP 'Hoover type sprayer' and hope for the best !

Be careful of blooming if damp.

If you are using a topcoat which is acrylic - go direct from nitrate to topcoat - no butyrate. if you are finishing with butyrate, base of nitrate and then build with butyrate.

Make sure you use the anti bloom additive.

[maxmotoring]

Hi Mike, Thanks for the reply. I have a temporary spray booth in my garage. I have a compressor and conventional spray gun. I have also borrowed an Apollo HVLP gun and turbine. The top coat will be a Butyrate finish. I have plenty of retarder.
Just wondering what the pros and cons of each system are, and which one has most favour in the community.
I cannot see the Spiegen HLVP gun mentioned anywhere on line.
Rgds, David

[mikeblyth]

As mike says, with butyrate, base of nitrate and then build with butyrate.
Very straight forward. Get it wrong disaster. Suffered this recently.

[mikeblyth]

Sorry, should have explained thought I Had a good nitrate base wrong

[JimCrawford]

I've used the Apollo HVLP for Ceconite Nitrate/Butyrate recovering. Once set up no problems and a good traditional semi-matt finish.
Even though the HVLP system has less overspray than a standard compressor and high pressure gun, you still need a good extractor fan to keep the air clean, good lighting to see what you are doing and an appropriate solvent mask to avoid getting high on fumes!

Jim

[maxmotoring]

Thanks Jim, very useful. I did some spraying (a nitrate silver rejuvenating coat) on Saturday using the Apollo HVLP, but had a lot of inconsistent results with the spray pattern, the nozzle seemed to want cleaning regularity, not sure if it’s an old gun. When it was working it was good.
I did filter the paint before use. I would hate it to go intermittent on me on the final coat, hence the request for advise.

[tnowak]

I used a traditional compressor but with a HVLP spray gun from Amazon (BERGEN Professional HVLP Gravity Fed Spray Gun 500ml Capacity 1.4mm Nozzle BER8742 ).

Worked well for me but my advice is to go for good quality/professional guns.
Some of the cheaper ones don't get on well with the solvents in butyrate etc.

Make sure you wear a good quality face mask suitable for solvents paints. I found the Moldex range with replaceable cartridges worked very well.

Tony

[mike newall]

Sorry - a 'p' got in there...

Siegen gravity HVLP gun is what I have.

1.3 nozzle, sprays really well at 40psi at the outlet.

[maxmotoring]

Thanks for the replies. I have made the decision to go the traditional route and buy a good (Devilbiss) spray gun. I have been told that strangely cellulose needs a larger nozzle than other paint, so have gone for a 1.8, I can always turn the volume down.
I am intending to Tee in 50 litre and 25 litre compressor to give extra capacity. Thanks again for your help.

[mcfadyeanda]

A good spray gun is like a good camera; I wish I had the skill to use either really well!
Poor gun technique is rampant on TV car-makeover programmes, so don't copy them (but their 2K paints can be forgiving of a multitude of sins).
ICI (paints) used to publish a very good book on technique.

Duncan McF.

[tnowak]

If you are doing a lot of spraying it is good practice to build in a water trap/filter/ pressure regulator.
In our humid climate you get quite a bit of water out of a regular compressor.
Info on-line or I probably have a sketch of what I did somewhere.

Tony

[maxmotoring]

Well, the rejuvenating nitrate coat all went to plan with a nice sheen, the Devilbiss gun worked well. However the butyrate silver coats have a dull appearance and a rough powdery feel, possibly overspray. This can be removed with a cloth, but it still leaves a disappointingly dull finish. Is it usual for butyrate finishes to be less shiny than the equivalent nitrate finish. Have I done something wrong or am I expecting too much?
For info the butyrate was applied with workshop temperature 19C and humidity 43%. The dope had retarder thinner added to 30% mix. Gun air pressure, 30psi (as recommended) indicated while the gun trigger operated rising to 55psi while not operated. Is this too high?

[tnowak]

I recall that the Randolph silver butyrate is dull in appearance and certainly not "shiny".
I think you do have some overspray and silver makes this more obvious.
Even final coat coloured butyrate isn't that shiny like a two pack finish would be..
However, using T cut will give you a good shiny finish but it is a lot of work..
Tony

[mike newall]

Are you staying with a silver finish as final colour ?

If so, there is nothing wrong with blowing a clear butyrate over the silver as a 'top coat'.

Do not go back to nitrate and if you are considering a 2 pack top coat - oops, too late, you go nitrate to top coat.