Help with spraying please

[Smouser]

I bought the Wolf Dakota compressor last week and yesterday I have had my first go at spraying with a compressor with mixed results. I could not get the spray to a fine mist.

Setup as follows:
Wolf Dakaota 90ltr compressor - water trap - hose - small water trap - spray gun.
Granted the spray gun is only cheap https://www.amazon.co.uk/Silverline-783124-Gravity-Feed-Spray/dp/B000LG0VMU and I dont expect to get AWESOME results from it but I do feel I should have had better results.

I used HMG Speeddline C71 paint - https://www.baileypaints.co.uk/indu...ck--1k/_file/551/c71-speedline-datasheet-pdf/

I thinned the paint with recommended thinners up to 10% but it did not seem to make much of a difference.

The main problem I have experienced is there seem to be a fine mist of spray but with it there is also little "blobs" of paint.

While I am overall pleased with the outcome of the door, I would like to sort the problem out so that I can get a smooth finish on other items.

Please look at the attached pictures especially the close ups.
Any help appreciated.

 

[ajlelectronics]

1) it's a Silverline
2) you may need more air pressure.
3) you may need a larger nozzle
4) you may need to go as far as 20% thinners.

 

[Burdekin]

How did you setup the gun and have you got a pressure gauge on the gun? Set gun pressure about 30psi at the gun, fan knob fully open and fluid knob two turns open. Should be about right.

 

[Smouser]

Thanks for the help so far. I dont have a pressure gauge at the gun yet. Will get one soon and try all the recommenations.

 

[ajlelectronics]

Thanks for the help so far. I dont have a pressure gauge at the gun yet. Will get one soon and try all the recommenations.

Then you are working blind! A seasoned professional can do it, but a beginner doesn’t have a chance.

 

[pedrobedro]

It looks like you are not thinning it enough and holding the gun too far away. Pull the trigger on the gun to the first stage for air only and check the regulator pressure with it open till you get a gun mounted regulator (I never use one I always use the line mounted trap/regulator)

 

[carbon]

The viscosity that the paint should be thinner to when spraying isn’t mentioned on that TDS, but it is on this one https://portal.hmgpaint.com/pdfdatasheet.aspx. Which may help achieving a better finish

Edit: Sorry link doesnt work as you have to register on hmg's website to view tds

 

[steveo3002]

id suggest more thinners

set up some scrap for test purposes , and have a play with a small amount of paint , just keep adding a dash off thinner and try spraying it until it goes on nice and smooth , yours looks like how almost un thinned paint sprays

 

[Smouser]

Carbon - Thanks for that. Can you tell me what it says?
As a rough guide how thin should paint be when trying to spray it? Easy running like water or thicker?

 

[ajlelectronics]

Get yourself a viscosity cup. The thinning is correct when it takes between 30 and 35 seconds to empty according to that data sheet. It also says 1.6 to 1.8 nozzle so yours is a little small.

 

[carbon]

Have found these two pdf’s Which hopefully explain a bit easier. http://www.lemmer.com/pdf/Chart_Viscosity.pdf

Haven’t seen b4 mentioned on auto paint TDS ( usually ford 4 or din 4) before but have found this other conversion chart that has a b4 cup listed but not sure if it’s the correct one http://www.pexa.com/resources/pdfs/Viscosity-Conversion-Chart.pdf

 

[Burdekin]

Start with the basics first; gun set-up and about 6inches from surface. If these are correct then look at thinning more or getting a gun with a 1.8mm or 2mm nozzle. If you haven’t got the gun setup and pressure about right no point in messing with paint viscosity, still won’t spray properly.

 

[postie jon]

looks like what i had yesterday ,same prob, too small an air cap, not enuff thinners & and paint needs straining ,its gets us all.

 

[Smouser]

Thank you all for the help so far all good advice. I tried again today. Slightly better results. Experimented with pressure/distance/thinners until I got bored replacing brown paper as test pieces

Door doesn't look too bad. Waaay better than what it was and better than what I can achieve with a paintbrush

I will try a bigger nozzle next time and practice practice.

 

[Morrisman]

I have only sprayed acrylic paint, but that required a hell of a lot of thinners or it came out in just the droplets you describe. I think i was added 50% thinners.

I also fitted a pressure gauge at the gun, as rhe pressure dropped markably after a 20’ length of hose. You need to check the gun pressure while air is flowing, not when it is static. 30% drop is normal.