Hi All I'm trying to spray a2K gloss clear coat at a ratio of 2 parts clear and 1 part hardener plus a slash of thinners.. I've a 3hp comp with water trap fitted and a brand new 1.2 mm movac spray gun with movac supplied 2k clear coat.. I'm guessing it's a temperature or press prob but I'm getting like a misfire as I spray and some bubbles in the cup .. So the finish is blotchy.. I've no heat on in my workshop at mo but can have if required.. In other words my workshop is the same temp as outdoors.. (Today not cold but rainy) Not sure what pressure to use either.. I've used panel wipe to prepare surface etc and a tack rag.. Any ideas please..
I'm no expert but I think it depends massively on gun type , but I run 45 - 50 psi , temp also important usually try to get my work area upto 70deg,
I can't understand why you would get bubbles in the cup. Is it a gravity fed gun (cup above the air cap) or a suction fed gun (pot below the gun)? It may be a material supply problem. Check the vent on top of the cup / pot isn't blocked. This works like a breather on your fuel tank. If blocked the material would have poor flow or would spit.
Several things to consider here. Is it MS or HS (medium or high solid) as far as the lacquer goes. I used HS in a 1.4 tipped touch up suction gun recently without any problems at all to spray some wheels and that was outside a few weeks ago. Is your pressure correct for the gun, it sounds a fraction low. Have you thinned the lacquer enough, it should be anything from 10% to 30%. Do you have the correct settings for the gun in terms of fan width, needle retraction and air pressure if it's an HVLP gun or just gun pressure and needle retraction for suction cup. If the paint is too cold it won't flow correctly. As for outside temperature it is moisture content in the air that can be the biggest problem. You can use a faster setting hardener if you are finding the temperature too cold. Bubbles in the lacquer as it sits on the surface can be caused by spraying too close to the item, too much air pressure or too much paint sprayed in one pass, along with too thicker paint possibly which is not allowing the air bubbles to escape in time and they are setting in to the lacquer All the above can or will have an effect so you need to go through things carefully and eliminate each one. I suspect it's a combination of a few things and a higher temperature environment may help towards making life easier. Get the lacquer up to a nice high room temperature before mixing and use the makers mixing ratios as a strong guideline but for more flow in colder weather use more thinners or thinning agent especially with HS lacquer which can be very thick depending on make. I hope this helps a little.
Yes, I work very early in the morning and finish by 3pm, that way I don't get disturbed by phone calls!!!
Hi Red.. I've tried spraying it at a pressure of 60 psi .. The gun is straight out of the box 1.2 mm the bubbles are not in the paint surface they come up in the cup as you try to spray.. The hole in the cap is clear too.. The manufacturers ratio is 2-1 which I've followed with digital scales, I've then added 25% thinners.. But no luck.. Initially the gun sprays quite heavy then it goes really light, if I trigger off and go again it's exactly the same, heavy and then light.. With bubbles rising in the cup.. Thanks for your help NOODS
Normally one would use a minimium of 50% thinners, even with this mix there will be an orange peel finish requiring some light sanding. The final finish coat is usually 75% to 80% thinners, but this depends on paint brands. It could be that the two pack paint mix is just too thick. If you increase the pressure it would help but never higher than 80psi. Strip the gun and make sure all the internals are tight and the gaskets properly seated.
Are you getting problems with a pressure drop or clogging. As above I would strip and clean the gun and check if it is performing as it should. Try straight thinners to see what spray pattern you are getting and how the gun is performing under normal spraying with a full tank and when the tank goes on to free air delivery. If the compressor cannot deliver the pressure, which it should be more than able to then this will cause the gun to start under performing. Failing that your paint mix might be too thick but if that is what the manufacturer is quoting then it should be quite close. The gun of course could have too smaller a tip to produce the result you want. Unfortunately this is a case where you need to look at all that is going on to determine if it is a paint problem, a gun problem or a pressure or blockage problem. Is it an HVLP gun, it sounds like it, in which case you will get bubbling in the paint container but it should not transfer to your piece being sprayed.
Hi Red No pressure drop .. 3 hp comp with 15 l tank.. Clear coat above Gardner above.. Rec. ratio 2-1 .. Didn't mention thinners although Ive tried it..
I have used the above with no problems, and I have often bought in bulk from Jawell paints. You should have no problems with the recommended ratios. I would look to the gun or your settings. Have you tried it with straight thinners yet. If this fails then you might have a gun or pressure problem
Yes met just tried it and it's fine.. Do you thin the omi crom then ? I'm guessing it must be a temp prob then .. ( surely a brand new gun can't be faulty.. It's first time I used it)
Yes, I use the fast thinners when I use this product. Currently I use Octoral HS clear coat which is very good and gives a very high build and a nice lustre. http://www.octoral.com/en/products/non-voc/clear_coats It's always possible you have a gun fault but I would now look to the ratio of clear coat to hardener and also how much thinners you are using. If it is too cold to practically spray where you are you could try mixing using a viscosity cup and that will ensure you have the correct viscosity for your environment. http://www.ebay.co.uk/sch/i.html?_from=R40&_sacat=0&_nkw=viscosity+cup&_sop=15 At least things seem to have narrowed down a bit but I still think your tip on the gun is slightly small, I use a 1.4mm on my HVLP gun and that is fine, although there is no real reason why a 1.2mm should not work. Are you happy with the needle retraction settings and also the gun pressure. Do you use a pressure regulator on the gun as well as a regulator on the air supply. The gun might need a bit of fine tuning. I hope this helps and as mentioned before it looks like a bit of a trial and error thing until you can nail down what the exact problem\s. Good luck.
Dear Red I think I might have caused one of my issues.. Movac gave me a new gun and initially it worked a treat until I cleaned it.. I found that to get the needle out I had to depress the trigger slightly and loosen a small fit between the front of the trigger and the nozzle body .. Pic below to give an idea for it's location.. If I did this nut up tight it stopped the needle from closing as it should... Am I correct that this should be left a little loose? I sprayed my 2k lacqure and the only problem I've got now is that after 3 days I can still stick my finger nail into the surface.. If I buff it it removes the laq.. I used a 2-1 ratio as per manufacturer req...is it a temp issue do you think.. It's a shame as other than that it was great.. Cheer NOODS
I can't quite see from the photo you posted but I think you mean the packing that is behind the trigger. If you tighten up the nut in that area then it will affect the trigger action and you could encounter all sorts of problems when spraying like the trigger sticking on too long or not retracting the needle properly or passing air through the gun correctly. Just adjust it until you get a smooth action and no leaks. If you do have problems then you might need a new packing washer but you may also be OK to send the gun back. Are you still mixing by weight? if so then possibly your ratios could be wrong. I noted one primer product that required 4 to 1 by volume but 7 to 1 by weight. You may be better going for volume if you are still using weight. Check the data sheet from the manufacturer With lacquer it does tend to take longer to dry and even longer to harden fully. As mentioned I lacquered some wheels recently for an LC. It took three days for the paint to be hard enough to handle the wheels and even then it was still soft. You could try a faster hardener or use more hardener beyond the 2 to 1 ratio. Is it Omi-cron you are still using as I have had no problems in the past using it at 2 to 1, but that would have been in warmer weather than now. If you have no bubbles in the part you are lacquering then you may want to just denib it and do a few more coats to get an even surface and then just leave it to harden over as long a period as you can. A warm environment will help lacquer cure quicker, so indoors would help the hardening process, but it will take a few days, mine took three in a warm environment so outside it could have been five even. By now you will have noted that lacquering something is, or can be, harder than just spraying a gloss 2K paint. So when it does harden rub it down with as fine a wet and dry paper you can get away with and realistically no more than 1200 as if you use anything too harsh it will scratch and be much harder to fully compound out. I always aim for 2000 grade and then go to 1500 if I really need to. You could test a piece first and see how it compounds using a fine grade and then go from there. It's also best not to use quick cut compounds as they too leave scratches. Finish with a good fine compound like Farecla G10 and after that you could even go finer by using a paint restorer. I hope this helps, come back to me if you need more.
Red... Your pretty much spot on mTe ... The nut by the trigger has been doing exactly what you said.. It was too tight and stopping the needle retracting.. There's no instructions with the gun at all so for a novice! Yes I weigh out my clearcoat at a 2-1 ratio.. And yes I'm using the omi-cron ... Ive also got the G10 and G3 fareca and before that I rubbed down with P600 and then 2000 and then 3000 all was good until I used my fareca foam compound mop.. Using that it ripped off the lacqure.. Again no data sheets provided with the omi-crom... Poor really ... I will try a little more hardener and leaving it in a warmer place... Thanks Red
Try doing it by volume and get some plastic mixing cups to see if that helps. Here's a link to the data sheet you will note the instructions state to mix it by volume as opposed to weighing it. This could be where you are having problems. http://uschem.com/products/docs/SS_Omi_Cron_7200_Euro_Clearcoat.pdf You will also note that the suggested gun tip is in the 1.3mm to 1.6mm range for both HVLP and Suction guns.
