Spraying Advice

[Concrete-crusher]

Hi I have sprayed my bonnet for the 1st time using cellulose filler primer on an isolating coat.

Its my first time with a spray gun rather than cans so I'm learning as I go.

I have attached a video to this link

https://www.dropbox.com/s/630bn9cq074bm ... d.m4v?dl=0

and would welcome knowing where I have gone wrong. The end result had some runs , so before i rub it back and do it again , id like to understand this abit more.

I used 30psi , and thinned the primer/filler with 20% thinners as per the manufactuers instructions.

I set the gun to produce a nice rugby ball type pattern before starting.

Thanks Steve

[Bud English]

Coincidentally, I've asked Randy (Sea Ranch) to PM me with information or to start a thread on his use of a spray primer mentioned in a recent post. I thought a thread on home resprays would be well received by some of us DIY folks. Now here you've started one. Thanks for that. I'm looking forward any info provided by those that have successfully tackled this on their own as well. There may be more than a few of us interested.

[Concrete-crusher]

Ok 6 hours later and the bonnet looks much better as its dried out completely , and it's really just one run on top. See picture.

I'm wondering if I should have allowed more paint to flow and sprayed faster ?

Or should it have been less paint and slower ?

Btw cellulose paint in the UK is restricted to classic car use now , lucky me

It will be interesting to see what others think.

Steve

[Grizzly]

I'm a painter by trade and don't take this the wrong way but your messing about too much, you should paint the sides then straight onto the top of the bonnet don't keep going back you blow bits in (don't let the over spray have time to flash or you will need to over apply to get it covered which in turn drops your gloss level etc)

It may be the video but the gun seems to have a poor fan pattern (only looks about 2" wide?? and with the gun quite far away too) I know this isn't cellulose but you get the idea how to set the gun up and the correct overlap/speed https://www.youtube.com/watch?v=QLH83B0Q2qE

I'm assuming you flatted the Primer before applying the top coat too?

Frankly, if its your first time you should really have practiced on some thing first, also i'd have used some cheap 2k rather than Cellulose. I know every one says how easy Cellulose is to work with but honestly its very hard to get a good quality finish on and it doesn't stick to GRP anywhere near as well as some of the modern primers. So if you are deliberately using Cellulose to match the rest of the car things like a quality gun with a nice big fan comes into play and there is no getting round it practice makes perfect.

I'm wondering if I should have allowed more paint to flow and sprayed faster ?

Or should it have been less paint and slower ?

This is where practice comes in, it's either move fast and close or far away and slow. If you do a test panel you can slow down or get closer until you find a nice speed/distance that suits your style. The idea is to get a nice uniformed coat on that you don't need to double head (go over area's to wet it up) its all about consistency.

[Concrete-crusher]

Thanks Chris , that's exactly what I need to know , I did think at the time maybe I should just stop after one pass on the bonnet.

I will try getting a bigger fan next weekend , it's a divilbiss gun , new but discontinued and no instructions. Their seems to be two paint screws , most of the guns I have watched on youtube etc only have one.

I will keep practicing before moving onto the rest of the car.

Regards Steve

[Grizzly]

Gravity feed Devilbiss guns are all the same basic design, if you look at the picture below 9 is the Fan screw, 16 in the paint Volume screw. In a nut shell, the top screw should be turned all the way out then 1/4 back in, the Volume screw is a personal preference thing, i have mine fully out if its direct gloss but you can balance your fan pattern by hanging some paper on a wall and make a pass at your speed and gun distance, you can wind it in until the very wet patch in the center doesn't move with the air (if you notice the spray pattern picture i've put below the left hand dot pattern has a line where the paint is so wet the air coming from the gun has moved it) As for air pressure, 2 bar or 30psi at the gun is about right but make sure your compressor isn't dropping that pressure as you paint i know it often takes a meaty compressor to keep up with a Gun (do you have a gun regulator to check the pressure? because if you set the pressure at the compressor it will drop by the time it gets to the gun)

Do you know what set up is in your gun? (what size Fluid tip and Air cap is fitted (parts 1 and 4 on the attached picture))

When you said you had a Rugby ball shaped fan did it look like this?

[nigelrbfurness]

Comparing it with my own technique, you look too close to the job, with too narrow a fan. All you need is a bit of practice. I tend to use 50-60psi with a gravity fed gun.


Cheers
Nigel F.

[KevJ+2]

I used to use my old Binks Bullows gun until it broke, so I bought a DeVilbiss thinking they would all be good.
My MG that I sprayed (3 years ago) was with the DeVilbiss SLG and it was the worst spray gun I have ever used.
I admit it's their cheapest model (about ?60) but what a useless item!
I think you could buy some other Chinese copy that would do a better job.
Kev.

[Concrete-crusher]

Update , I have now got the gun producing a bigger fan and spraying the cellulose quite well.

However as soon as you get a good gloss , you can see where the filler has gone.

It seems very hard to blend in by dry sanding alone ? I'm using P400 discs

Should I be sanding more or spraying more hi build filler primer ?

Steve

[Grizzly]

Update , I have now got the gun producing a bigger fan and spraying the cellulose quite well.

However as soon as you get a good gloss , you can see where the filler has gone.

It seems very hard to blend in by dry sanding alone ? I'm using P400 discs

Should I be sanding more or spraying more hi build filler primer ?

Steve

Cellulose has quite a high Solvent content which is why it searches (lifts edges of primer and sinks into repairs (makes islands)) this is why you need to practice a bit, you need to find a happy medium (too much product and the solvent will attack the primer, too little and it will go orange dry. Both too heavy and too light will drop the gloss levels)

400 grit Da disks are ok but i'd always want to hand finish with wet/dry 800's at the primer stage, do you guide coat your high build? it really does help to see if you have got the High build properly flatted. (also try to dry as you go as watermarks can be a paint to get rid off)

I'm not an expert at using Cellulose but i've done a few repaint with it in the past, as i use 2k MS,HS,UHD and Water its a shock to the system when a customer requires the "Original" finish (Cellulose). I don't know if you have the proper old school stuff but the reason i say its hard to do a nice job is i'd build it up over say 6-8 coats starting quite thick and slowly thinning the paint until it starts getting quite transparent (its done very much by feel and the old school painters just splash a bit more thinners in (no rime nor reason to it)). After the first couple of coats (when its covered) i'd 1200's the lot off with soap/water (don't go through anywhere or you will be in trouble) and then only de-nib as i bring the shine back. It does build up quite fast as the Cellulose tends to dry fast (can get a full repaint done inc flatting in a day easy)

Cellulose is VERY reactive so the more Solvent you put in the more chance you will get a reaction so be careful.

Then you have the Polishing, Cellulose does dry very flat if its been done well but unless your using Metallic Cellulose you will need to re-flat with 1200 and polish it back up to get a nice deep finish.

Not too late to use 2k MS you know 2 nice coats and your onto polishing. I don't want to scare you but Cellulose does take some practice to get really nice, i wouldn't recommend it tbh. MS 2k is the starters paint of choice, anyone can get a decent finish on it and you can drop 50% clear into the last coat that will stop it from Oxidizing and give you a nice gloss (the trade off though is it stays open longer so tends to pick up more nibs which means more colour sanding when dry)

[Grizzly]

I used to use my old Binks Bullows gun until it broke, so I bought a DeVilbiss thinking they would all be good.
My MG that I sprayed (3 years ago) was with the DeVilbiss SLG and it was the worst spray gun I have ever used.
I admit it's their cheapest model (about ?60) but what a useless item!
I think you could buy some other Chinese copy that would do a better job.
Kev.

I agree, being in the trade i only use the top end guns but the difference between a ?50 gun and a ?600 gun is huge.

Buying one try and steer away from HVLP guns as they require a monster Compressor, aim for what they call Compliant guns (easier for the Compressor to cope with).

If i was going to advise some one buying a Spray gun i'd tell them to go for a second hand Devilbiss GTI myself (Gravity feed 110 air cap and 1.4 fluid tip ?30-60 on e-bay get the later Anodized ones as the early Chrome ones arn't that hot) i also like sata guns 3000 rp up but you will pay more for one of those and they use more air but they have great fan's (the layout and feel takes some getting used to though), if you want some thing for smaller work my all time fave is the Iwata w400 (best gun i've ever owned but the fans on the smaller side so wouldn't want to repaint a car with one) I'd also try to steer away from Suction feed guns, the idea is good having a bigger pot etc but in practice a Gravity gun will always work better and use more of the paint in the pot.

Some thing else you might want to look at is 3M PP cups, they might be expensive to set up but there great, Very easy to clean your gun, Self filtering, spray upside down. (sound like a sales man) but i've used them for 10-15 years and just great (as long as you click the lid in properly) http://multimedia.3m.com/mws/media/8006 ... ochure.pdf all that said may be a bit extreme for the hobby painter.

I admit i've not used any Chinese copy guns but the ones i have seen seem to be Sata copies, not sure i'd pay allot for one as these things tend to fall to bits in your hands but in theory it could be a good gun.

Another option is the Turbine style HVLP set up that doesn't use a Compressor like this http://www.hvlp.com/products-series/ i had a demo of one and it did work well but there not cheap for a good one (i'm told you can hire them from good Tool hire shops) wouldn't be my fave solution but would do the job i suspect.

[cabc26b]

+ 1 for the Iwata - LPH is still my favorite

[Concrete-crusher]

just an update , I,m quite pleased with the result , I sanded out the paint blisters , filled with polyester gel coat filler left over from my boat , wet and dryed with P400 , applied a barrier coat to the filler , followed by primer , and top coat 1st 50/50 , 2nd 33/66 used P1500 wet and dry then finished with 3rd coat 25/75 (cellulose/thinner)

The comments posted above gave really helped.

Thanks

steve

[KevJ+2]

Well done Steve, looks really good.
There's a lot of pressure to spend many thousands on painting Elans so top marks for your bravery!
Kev.

[Grizzly]

Looking good

Have you given it any polishing yet? I know with Cellulose you can't beat T-cut, you can use modern polishes but i've never had as good results (old cutting compound followed by a t-cut). Unfortunately Cellulose loves elbow grease, you can machine polish it but take it very easy on the edges.