Question
I'm trying to achieve a perfect finish with polyester (ICA). I use a Fuji 3 stage HVLP turbine system. I spray paraffinated ICA polyester that is base material plus 2% catalyst and 2% accelerator. The ICA material is absolutely beautiful - very hard and polished to a mirror shine. The problem is that I don't know how to achieve satisfactory spray quality and how to rub it out properly.
Currently, I spray 3 - 4 coats of polyester with 15 minute intervals, as per their technology, then dry for at least 48 hours. The material right out of the can is very dense and demands to be thinned with purified acetone. However, the more you thin it, the less it is able to get coated with a layer of paraffin when dry - there is a fine line. I have to keep it dense enough and yet be able to spray it. Quality of spray exhibits some orange peel and cannot be polished with compound directly. Rather, I must sand, starting with 400 and ending with 1600, which is very labor intensive.
The problem with sanding is that it is difficult to stay within a single spray coat--in some places you go through to a second coat, exposing the boundaries. After that, when I follow with a series of compounds, I see swirl marks. It turns out that once you touch the surface with sandpaper, it is virtually impossible to remove swirl marks, no matter how careful you are or how much time you dedicate, especially when you deal with large surfaces.
Forum Responses
It's very tough to start with 400 grit paper and go to 1500 without screwing up somewhere and leaving scratches from the last paper, or making sure you removed all the grit and stuff after sanding each step.
I would forget the paraffinated poly and go with direct gloss poly or polyurethane instead. Which ICA product are you using?
I use all automotive products for rubbing and polishing. They seem to have a product for every purpose.
I did a conference table several years ago, over 16' long, using this system. The customer thought it looked nicer than his brand new black Jag!
If you were to look at my finished product you would not know it was 90% polyester and 10% urethane. The urethane is very durable, but what's nice is it's high in solids, but it lays on the surface with ease. Also, the compounds are made for these materials specifically, so they work hand in hand.
Urethane is not as hard as polyester. Hardness as well as thickness of the finish is very important to me. Urethanes can not be built as thick as polyester can. I have gone through the entire line of Mohawk finishing products including their ultra-catalyzed clear coats. They are just not what I am looking for.
My production is high-end speaker cabinets. When you do a table, you are dealing with a single surface with no joints. Speaker cabinets have many joints. The finish that I use must be able to fill and hide the joints and withstand the test of time, not sinking into the joints.
Strata 800 (removes 800 grit sand scratches)--I applied this compound with a 12" random orbital polisher equipped with genuine lamb's wool bonnet. I managed to get rid of all sanding scratches. They then recommend using their Chroma 2000 and then Aurora 3000. However, I did not have those and finished with my 3M hand glazing compound. That was the surface I was looking for. It could be scratched with a soft cheese cloth! I believe I need to get their finer compounds and try them also.
I should get a gravity feed as suggested and dump 3 - 4 thick layers for polyester. After that, the surface will obviously be rough with orange peel. However, the thick last layer should allow to cut it smooth with sandpaper (320 - 1000). Then I will follow with my compounds.
It would be ideal I could find a way to dump polyester without thinning and get good atomization and a super flat surface. My spray booth, however, does not have water filtration. I should try that spray gun. After screwing with the Fuji system for two years, I don't particularly like it.
You may also want to look at reducing the amount of accelerator in the polyester if you are showing your coats underneath. When polyester is properly applied, you will have just one extremely thick coat with no sign of the layers underneath. You can use your primer to level and fill, then grind it down with P150-P220 sandpaper. Then topcoat with the direct gloss polyester. Direct gloss lays down better then pariffinated. Polyester as a rule generally will not lay down smooth, but you should see a big difference between the pariffinated and direct gloss.
Your buffing schedule also needs improvement. With polyester, you want to level first with an aggressive paper, then the rest of the sanding is just to remove scratches. Starting out with a lower grit paper, then stepping up in progression to 1500 grit. Depending on how rough the polyester is before sanding will determine the grit required to start your sanding schedule. It is not unheard of to start sanding polyester with a P220 grit, then move up in progression to 1500. This may sound strange and time-consuming, but you level with the aggressive paper and just remove scratches until you reach the 1500 grit.
We also used 3M microfinishing film to do our sanding. It is available in micron grits. I used 20 micron, then 15 micron and finally 9 micron--this is available in a 6" diameter adhesive disk to use on a Dynabrade sander with a NEW, FLAT pad. Wet sand, using water.
You will not need to do as much buffing with this system. Finally, and probably most important, is your buffing compound. The VERY best I ever found was Sadolin Canada's Pasta Abrasiva, which I am no longer able to find. I tried many different compounds with extreme frustration, for as you know polyester is very difficult to buff if you do not have the proper compound. I too have used a catalyzed automotive urethane over the polyester in some situations, mainly due to the ease of buffing. Also, I used a Binks 2 quart plural component gun to spray the polyester, which made life much easier.
I find especially valuable your recommendation of 3M microfinishing film and Dynabrade sander. That is something I need to try immediately. With the process I am currently using, this may be the last link to success. Manually I am unable to achieve absolute uniformity and consistency of the surface grit. Often I finish with grit 1000, but in reality there are some deeper grooves which you absolutely can not see, until you start polishing. If you go back and try to eliminate them, you will scratch the surface in other places. Using 3M microfinishing films along with the machine may solve that significant problem.
The quality of the surface I am looking for exceeds car finishes. I am looking to get absolutely uniform tiny polyester grain without the surface looking like it's been polished to hide imperfections. I can easily get it to deep high gloss and black mirror now--however, not for the critical eye.
Speaking of component spray systems, can paraffinated polyester be applied successfully with component spray? So far, I see three obstacles:
1. Catalyst and accelerator must not be mixed directly with each other. Even though they are mixed in the air stream, is it still safe? Mixing those two components directly results in lots of heat.
2. Mixing catalyst with base and accelerator, causes normal chemical reaction between them during which the mix must dwell for 5 minutes. In that time lots of air bubbles appear and escape the mix. If mix is not allowed to stand for 5 minutes and sprayed directly after (or during) mixing the components, those air bubbles will form on the surface being sprayed.
3. There is no component spray system I've heard of which is capable of providing mix ratio of 1:50 which is required for polyester formulae (2% catalyst and 2% accelerator). No acetone should be added if possible, as it degrades quality of the finish and may impair migration of paraffin between layers.
What about it?
I use purified acetone supplied by ICA.
A rep from ICA suggested that excessive thinning with acetone (beyond 5%) impairs the ability of paraffin to migrate to the top layer.
On my previous post about component spraying: I think it is possible to reduce the number of components and mix ratio to manageable limits. I think I can premix accelerator with base and catalyst with base. Mixed separately, they will not cure. They will only cure once mixed in the airstream in 1:1 ratio.
I just had a crazy idea: since I don't have access to a component spray system, why not attempt using two guns and arrange their streams to intermingle? Will this work?
You are probably correct on the acetone in the pariffinated polyester. I have yet to work with pariffinated polyester and know that it is sensitive to temperature changes and important for the pariffin to move to the top. They may have a polyester reducer that dries slower then acetone that could help you on thinning the material. We don't use ICA and I know that different paint companies have different specs, but the technology over one manufacturer to the other is basically the same, as there aren't any trade secrets in some areas. I do think you should consider a direct gloss and polyester primer underneath. There is a reason for this that I won't mention here.
Joinery is a whole separate subject. I spent around 2 years until I found a simple way to join MDF panels, so that the joint does not show up on the finish. You just have to do a long 45-degree miter joint and glue the panels together. This way, glue penetrates all MDF layers--the joint is very strong and stable. It will not move and crack the finish. Of course, you do not always deal with 90 degree corners and square panels. This method of joinery becomes quite an exercise then.
Component spray is interesting. Unfortunately, one has to spend a lot of money to get a decent BINKS component airless air-assist setup. Otherwise, a component HVLP pressure pot can be had for less. Despite the fact that I have learned how to lay polyester at full viscosity with my present HVLP gun, short pot life is still highly inconvenient.
As to my polyester status, I had another conversation with ICA. I am getting their polishing compounds to see how they work compared to the stuff I used. They also suggested importing some European carbide sandpaper.
Comment from contributor A:
I've been using polyester for some time. I use a product called Dura Tec Clear. It buffs out nicely and sprays perfectly with 5% thinning. It also builds fast and is free of pinholes if you time the coats right. I coat automotive interior plastics. Had some adhesion problems approaching 180 degrees F. Dura Tec solved that with a urethane/polyester barrier coat. Goes on thin, spray poly wet on wet. Gets me to 250 degrees F. I can absolutely deform poly prop. and the finish will follow with no failures. I need this performance for intense heat found in cars. Yes, I know GM only needs 220 degrees F but it is nice to be able to boil water on my work. As far as final finish, I used to use 3M Finesse (white) but found the haze it leaves very unattractive. Dura Tec sells buffing compounds that do well for me with no residual haze. I flat with 1000, go to 1500, then buff. Never use 400 - too aggressive and I find my labor is devoted to undoing those deeper lines. Also, don't buff the part immediatly after sanding. Do it the next day, or at least 6-8 hours later. Sanding exposes the innards of the coating, allowing leaching of aromatics which impede achieving that final high gloss. You have probably noticed that after walking away frustrated and coming back the next day to finish the job it comes up faster. Give it time.
The most recent company I worked for used a UV formula, and it looked very nice, but their problem (though they were more than ready to blame the cabinetmakers for improperly applying the adhesive to the veneer) was that the ultraviolet lamps they use heated the object more than enough to cure the film, but caused delamination of the glue as a result.
Another firm used polyester, and yet another used urethane. Because of the manpower they each had, they were, of course, able to produce outstanding results, but I'll bet if you were to examine their bottom line, they were losing money like a wild man. 15-20 people in the sanding room, either sanding or re-sanding (and many times, burning through the previous coat), 3-4 people in the "touch up" room fixing the screwups, 5-8 people in the spray room, and then 10 or so people in the polishing room, and three shifts and countless hours involved.
I was in the cabinetshop, and therefore, now that I have my own business and am attempting to achieve the same type of finish without all the hassles, I am looking for the best finish to apply without all those calamities.
I manufacture my products with varying wood species, some exotic. Obviously, some species have more open grain than others, and as I am using a very generic Minwax sanding sealer (looking for ideas here...) I think I am losing the battle from the get go. I am losing faith in the Minwax line as more "Harry Homeowner," since the results are less than expected. I educating myself about using powdered stains, better quality sealers, etc. Something I read recently led me to believe that there is some sort of spread one puts over the entire substrate, much like a thin viscous putty, and then lightly sands off, that is colored according to the species one is using (maybe one needs to stain this putty to suit).
After this product (the sealer, applied with 1-2 coats only) has dried, I Scotchbright this layer, clean it with Prep-Sol and then apply successive coats of Dupont ChromaClear Urethane #7500S. Since this is a catalyzed finish, each coat to coat and a half takes up one full day in my limited shop. And since I cannot assure a totally clean room (but do the best I can), I see some specks of debris here and there with each coat (creating even more work!).
I have to reduce the psi of my siphon gun (should look into a gravity gun) to about 20-25 psi. Therefore, I am required to sand the next three coats with 320 grit, and after the final coat I use 3M microfinishing paper, starting with 30 micron, then 15 micron and then 9 micron respectively, followed by rubbing and then polishing compound. Then and only then do I achieve the flat mirror finish I am looking for. But I am killing myself, adding way more hours than I can ever charge out to the job.
I am looking for better methods and chemicals to use to eliminate all this redundancy. My business is new, so I don't have the funding necessary to purchase a fancy spray booth, etc, but maybe I ought to look into polyester rather than urethane. You all have said that poly is harder than urethane. This would definitely help me out, since even after everything is finished and ready to ship out, the finish can scratch just by looking at it! You wouldn't believe the stress I incur while wrapping the items in 1/8" polystyrene foam and putting them into the shipping container. I thought about using Imron Clear, but I really don't want to play into Dupont's name game much more than I am. I am familiar with Sikkens but haven't personally used them. I will check out the few others mentioned. Getting a scale to measure amounts might be worth the effort, too.
To the person that originated this thread, building high end speaker cabinets, I commend you. You are really trying to achieve the ultimate gloss mirror finish. I wish you could see some of the furniture we built in these 40 million dollar jets. It would give you goosebumps! Just the galley (kitchen cabinet cluster) is $150,000 to buy finished (not including installation). Everything from start to finish had to be perfect, or they would bust your ass. I was not in the finish department, so I am in the learning curve here. But what I do know is construction (of course we used honeycomb materials, veneer and really strange fasteners to achieve this look, but you wouldn't be able to tell this).
I made an oath to myself when I started this business that I would never succumb to using pressboard or MDF to build anything but templates. I see this as cardboard. It is cheap, it explodes when it contacts moisture, it shatters when the least amount of stress is applied against it, and it weighs a ton. I could never use this stuff in my frames, for they would literally tear off the wall, and nearly double the shipping costs.
There is an old addage... "friends don't let friends buy MDF." You are building what I think are real quality speaker boxes, but why are you cheating yourself using MDF? You could go with Multi-Lam cabinet grade plywood, pre-veneered or not, in most any thickness, half the weight and double the strength, and the end line customer would know that his builder put the best quality ingredients into his product. I abhor MDF, particleboard or any other similar strata. Multi-lam plywood I accept. It stays straight as an arrow and costs the same (with the right vendor) or less. No MDF ever again in my house, unless it's for templates. You should see the Multi-Lam they have in Europe. 18 layers thick, striated in both directions all the way through, even in the 1/2" thickness. Hard as a rock, yet a 12' section is as straight as a ruler!
A clear reflection with no distortions starts with your purchasing agent. Despite some of the criticisms of MDF, I prefer to use a high quality MDF core to anything else that I’ve tried. I suppose there are probably some plywood cores that are good enough to use I just haven’t seen them. If there are any voids whatsoever in the core, even a 1/16 ’’, they’ll be apparent in your finished product if you look for them. Don’t underestimate the substrate factor, if you do, it doesn’t matter what you do after that, you won’t have a perfect finish.
The next step is to figure out how the product needs to be built. If you screw or staple into the core, you’ll see that too. I don’t mean screwing or stapling into the finished surface, I mean into the underside of the substrate. A slight compression of the core occurs when you penetrate it with a screw or staple and if you polish it enough to get that mirror reflection, and that compression will telegraph onto your film. I suggest a glue block be applied if construction allows, and then you can screw into that.
The first thing I do when getting started is to apply a barrier coat to the reverse side of the substrate. If it is a tabletop that is getting finished, then you need to apply the barrier coat to the underside. If it is a door, then apply it to the back of the door. If it is a door, it’ll be important to put the same quantity of finish to the backside as the front to offset the effects of the thick film. If you miss this step, the tension of the film will literally warp your product. The importance of this barrier coat is to lock in and stabilize the wood. Again, if you miss this step, you’ll be unable to achieve the still-water look and you’ll notice the grain of your wood slightly telegraph through the film. Most people don’t even notice this, but if it is polished correctly and you have a discerning eye, it’ll be apparent. This defect is the kind of thing you have to almost train your eyes to see like one of those cross-eyed 3D puzzles, but once you see them, you can’t see anything but them. A coat or two of finish will not due the trick, you need to create an absolute barrier. In South Florida most of the shops run without air conditioning and our high humidity causes the wood to swell ever so slightly. Once the job is installed in a customer’s air conditioned home, that humidity will dry out and that’s when you’ll see the defect.
I’ve been using ICS ILVA polyester, specifically the TG1323. I start with a 50/50 coat of TF25 Isolante and I apply as many coats as needed until the surface stops “drinking” the finish. The thinning allows the finish to penetrate deeply into the veneer and lock it in. After it stops drinking, I apply it reduced at about 10%. Until I get a decent penetration of any open grain. This stuff dries as hard as glass (or thereabouts) and I feel the more you put on (within reason), the less trouble you’ll have later. I like to get it to the point that the grain is no longer open enough to release an air bubble. It need not be grain filled, but enough that it has coated the inner surface of the actual grain. Again the reason being, polyester tends to flow over grain because of its viscosity, therefore air bubbles tend to be trapped in the grain and can cause a whitish spot within the grain. If time allows, I prefer to let this dry at least a day before moving on.
The next step is to sand the isolante. Before applying poly, you need to blow out all the grain with an air nozzle set to no more than 50lbs of air pressure. Anything above 50lbs can cause a static charge on your surface. In my experience, static charges that attract dust on your next film application are more of a problem on polyester or urethane than lacquer. There are also filters you can hook up to your air line that will eliminate the static charge. If need be, you can also wipe down the isolante with acetone so long as you don’t let a puddle build up, in fact, keep your lint free rag only as saturated as need be to wipe down the surface. If you are working with latex gloves, be sure they are the un-powdered type as well.
The next step is the application of your polyester build coat. This is where I use the TG1323. Depending on your environment, you may have to adjust the mixture from 1-2% accelerator. I like to flood the surface with very low air pressure to get better penetration of the grain. Obviously a higher air pressure will get better atomization, but it can also in some circumstances, prevent the resin from penetrating the grain due to reflection of the product from the higher air pressure. To my way of doing things, a lot of sanding is inevitable so I’m not too concerned about having a perfect film application. If you want still-water, you have to sand and polish a lot. If you want to get it done quick and don’t care about a slightly distorted reflection, then by all means crank up the air pressure. Two-part component spray equipment is ideal, but barring that, I just use an HVLP gravity cup gun. I have a guy doing nothing but mixing as this stuff kicks in 10 minutes down here and I’ll apply quit a bit (I’m not sure in mils) in 10 minutes. Of course it all depends on your application, when I say I apply a lot, this assumes a flat/horizontal surface.
Obviously a vertical surface is a different story. Very rarely will one application do the trick (for me) and the more you apply, the deeper your reflection will be. The Ilva product doesn’t have too much of a clarity issue, I’ve seen some other Italian stuff that does so you’ll have to keep that in mind. The Ilva poly does have a green cast to it so if you plan to have a deep reflection, you’ll need to adjust your stain/color a bit lighter and a bit redder to compensate. If I need to apply more poly, I’ll generally give it about 30 minutes to setup and then apply a second coat, maybe even a third. At this point, the spray environment is crucial. A positive pressure booth is ideal, but excluding that, you need to have a very clean work area including yourself-a bead of sweat on your brow can cost you a lot of time. Damp newspaper on the floor will help out.
The next step is sanding your build film. Most major imperfections can be handled with a fine drip file. Be careful how you sand out an imperfection. As you are going after that imperfection, you are also treating the surface around it and the tiny bit of extra attention to that area can show up in the finished product. I have no problem using 220 on a 6” DA. Make sure your pad is new and feels right. Some thick pads tend to grab and skip across the surface, I use a thin pad. Let the sander do the work, don’t get impatient and start bearing down on it. Keep the tool running just fast enough to keep a consistent glide across the surface - do not crank the air pressure on the tool all the way up. Keep the work area clean, a spec of something coarser than the 220 will cause you a lot of problems. You must treat the entire surface the same. Be methodical and use long strokes in one direction, than run counter to that tracing out an “X” and the go diagonally across and over and over again until you feel your surface is flat. I’ve also used blocks, but I prefer to use the sander for time reasons and maybe block it for the final sanding. It sounds silly, but you’d be surprised - hold the sander flat! Don’t get aggressive sanding at angles.
This is the tedious part of the work, but it makes all the difference. What appears to you as flat can be something very different once polished. Once I think I’m finished, I’ll sand it up to 320/400. Then I’ll take 220 and lightly go over the surface applying just enough pressure to keep the tool flat. At this point clean your surface and observe the scratch mark patterns. If you are flat, there shouldn’t be any areas that are shiny (relatively speaking). If you see areas that are shiny (from the 320 sanding), then you aren’t flat. Don’t sand the area where the shiny spot is, sand the entire surface again and repeat until the surface is free of the shiny patches. It is best to let your poly setup for 2 weeks before sanding if possible. This will allow the substrate and the build coat time to setup so there is minimal movement/shrinkage. If you sand the next day after application, and then perform the 320-check in a few weeks, you’ll notice it is no longer perfectly flat-it moves/shrinks.
Next step, I apply my gloss coat. I prefer to use a polyester gloss coat, it’s harder to sand and buff than urethanes, but the end result is a lot better in my opinion. Pretty much the same principles apply to spraying the gloss coat as the build with the exception of the lower air pressure. At this time you shouldn’t be filling anything and the layout quality of the film is the most important. You also don’t need as many coats, just enough to sand and buff without burning through. Again, I prefer to let this coat dry as long as possible, but I don’t think you need two weeks as there shouldn’t be much geography below. The longer this stuff dries, the harder it is to sand and polish, but it makes for a better reflection.
When I am ready to sand, I start out with 400 (which is pretty aggressive) and I work my way up to 600, 800, 1000, 1200, 1500, and then I use 2000 and 4000 pads. Sometimes you can get lucky and just start with 1200, but if there is a lot of sanding to do (relative to the 1200 grit) then you are likely to get frustrated with the lower removal and I tend to get more aggressive and that causes unevenness. It is crucial that the entire surface is treated the same. After 400, I’m wet sanding.
Finally, it’s time to buff. I start 7” Makita buffer/polisher set to approximately 1500rpms with a sheep’s wool buffing pad and 3M’s perfectitII compound (I prefer the 3M system as a whole over all others as a whole, there are some individual products that I like better). The longer dry times may require an extra cut compound. This is where the accuracy of your sanding pays off. Each step should remove the scratches from the previous step. If you fail to remove the 600 scratches with the 800, then they are there to stay until you go back and do it all over again - so be accurate. The compound should remove all sanding scratches, don’t advance until they do. Different people have different preferences for buffing compounds and polishes. I usually use at least 2 grades of compound before using a polish. The second grade will be applied with a 50/50 synthetic/wool buffing pad which is still aggressive, but less so than the pure wool. At final polish, I’ll use the synthetic yellow pads, but make sure they aren’t recycled automotive pads.
A few final words of caution - be careful with your buffing technique. As is the case with sanding, there is a tendency to hold the buffer at an angle to power out a troublesome area-this will affect your reflection. Use a different pad for each step, don’t use regular compound on a pad you just used extra-cut on. I think most importantly to buffing, be careful of your heat. The hotter the pad gets, the better it cuts, is partially why the wool pad is more aggressive. However, the hotter you get, the better your chance of rippling your reflection. The heat will actually cause the film to have a broad ripple effect or a 7” swirl or is you are really aggressive and get it real hot at an angle with a dried out pad, you can make the compound part of your finish.
So, that is my way of achieving a perfect reflection. If it sounds labor intensive - it is. This is not a quick way to a perfect finish and while there are steps that can be taken to have a nearly as good finish for much less time and money, it will still be “nearly” as good and like I said before, gloss not done right, looks horrible. This is one of those situations where you get back what you put in.
