Tag Archives: priming

January 2004 – Body shell spray priming

Body shell spray priming

Over the entire New Year’s holiday and, for that matter, for the entire Christmas holiday break the weather has been absolutely wonderful. We took advantage of exceptionally warm temperatures to open up the garage and spray the body shell with primer. The temperatures reached the mid-70s (Fahrenheit, 20+ Celsius), and so short sleeves did it, as you can see from the picture of Aaron spraying the right rear quarter panel. As everything was open and the fan was blowing, we didn’t use face masks, which probably weren’t necessary in this case. But we did wear ear protection because the compressor is so loud. In retrospect, I believe we should have worn our respirators, too.

Aaron isn’t too interested in doing the sanding, but he was ready to do spraying since it involved a new tool to play with and didn’t require tedious motion.

This was the first primer coat that was sprayed on, as opposed to brushed, and it went very quickly. Using a paint brush is a bit easier in preparation, but the real work comes with the block-sanding. It was very nice to see the coating go on without so much as a brush line anywhere, though Aaron was a bit too liberal with paint on the quarter panel since he left a few drip marks. These were easily removed with the blocking, though. You can see from the light lines at the top of the quarter panel that the blocking I’d done before has paid off in nice clear and predictable reflections. The quarter panels actually have been quite easy to do, perhaps because they are not large and flat surfaces. Flat surfaces and ones that require a long straight light line have been the troublesome ones for me.

As a matter of fact, two such surfaces make it impossible for this spray of primer to be the last. The outer sills (or rocker panels) are curved, of course, but the light line extends their whole length and it ought to be arrow straight. The outer sills are really shaped like quarter round moulding — quarter cylinders rounding out the connection of the side panels (and the doors) to the floor pans. Part of the problem (though not all of it) is due to the fact that I fabricated the left outer sill and it has a few irregularities that I need to work out. But I still am having some trouble getting the light lines on both sides arrow straight — it isn’t purely a matter of my fabrication methods (which were, I’ll admit, a bit crude). I think most of the issue is that the area is simply harder to work on because it’s lower and I don’t have a rotisserie to swing the area into easy access. The lower halves of the outer sills had at best a single brush coat of primer, and the sanding was difficult.

They’ll both need at least another spray of primer and blocking. The rest of the body shell is in pretty good shape, and I think that one more spray of primer will do the trick before we can spray color. The interior and the front bulkhead (firewall) will get no more primer. They’re ready for paint, after I sand the bulkhead a bit.

Spraying and blocking the body shell without the doors took two days. I did not spray the underside or the inside of the trunk (boot) nor did I block the front bulkhead or the interior. The bulk of the work was in the blocking the exterior sections of the car, and that was greatly simplified by spraying, as I said. The nice thing about using the brush in the first stages of priming was that it was easy to do small areas (like the detail section on the door that I did). If you manage to do all the prep, spraying the entire car is probably easier, despite the mess of spraying. Blocking sure is easier without brush marks.

Temperatures are expected to drop down to normal levels this next week, so I don’t think I’ll be spraying any more primer for a while. I also got a hold of some rock guard, though I decided against the 3M “Rocker Schutz” that has gotten a fair amount of exposure among the Jag restorers. The brand was recommended by a body fellow, and it has the added bonus of being a bit less expensive than the 3M product. I asked for “Rocker Schutz” by name, and we shuffled off through the shelves of stock to get it. He asked what I was going to use it on, and I told him. He said, “Let me show you something else” and we went off into the depths of the place. “I sell twenty times more of this stuff than the 3M,” he said. Now, I’m sure that “Rocker Schutz” is great stuff, but I figured I’d give this a try. The nice thing was that I didn’t have to shell out $60 USD to get the special 3M spray gun for this product. It uses a more generic aluminum low pressure gun, and the bottles of the product attach directly to the gun. I’ll provide more information later when I have a chance to use it on the underside of the car.

The body shell is virtually complete and ready for paint, so we’ll have to turn our attention to other things. That is a bit of a relief, to tell the truth. I am thinking that I will begin to study the IRS, and perhaps make some room in the garage to begin working on it. (The garage is a huge mess, I’m afraid.)

To close things up, a couple more photos:

December 2003 – Detail body repair, priming, sanding

Primer, sanding, finish prep

Patience is a virtue, I keep telling myself. If that is the case, I expect that people who do block-sanding and priming for a living are among the saints of the world. At least they are among the most virtuous, since it seems you can’t rush priming and blocking.The weather over the holidays here in North Carolina has been uncharacteristically warm, with temperatures reaching into the 60s (Fahrenheit, or about 15 Celsius). The garage has been nice and warm, and I have been able to do some more priming in shirt sleeves. As a result, the entire exterior and the body shell underside is primed. (Actually, there are small portions of the underside that need some primer — the front portion of the footwells that sit on the crude frame I made to hold the body.) On New Year’s Day 2003, we had just finished sealing the truck floor, and the car was still inverted. So, there has been progress.

The trunk floor was again something that needed some attention. When we put the car body on the rolling rack, we placed it on two two-by-four beams cushioned with styrofoam insulation. The body rests on the footwells and on sides of the trunk floor. In order to prime the parts of the trunk floor that were obscured by this set up, I first primed the housing for the IRS, let the primer dry, and then jacked up the trunk from the beams using some spare wood and two hydraulic jacks that float around the garage and elsewhere. (They’ve been wonderfully serviceable little jacks in their long history around here, jacking up old floors, a mud-bound horse trailer [twice!], and trucks in assorted situations.)

Anyway, the jacking opened up most of the space along the beams and all of the trunk floor for priming. As I mentioned, only the front footwells still need priming. So, after I’m done with the trunk floor, I’ll get those primed. I figure that I’ll get the “Rock Schutz” rocker guard on the edge of the trunk before I lower it, though.

All of these theatrics with the jacks could have been avoided, I know, if I had built or invested in an honest-to-goodness car “rotisserie.” Live and learn. If I ever restore another Jag, I’ll know better.

The front bulkhead (or firewall) is now completely assembled and ready for a final sprayed coat of primer and then some color. The picture shows the area partially blocked, since you can still see areas with the marker coat of spray paint. I put the marker coat on quite lightly. The footwell parts of the bulkhead came out quite well. I had to repair both of them last November. Check out the pictures of the footwell repairs and the front bulkhead as it was being dismantled. Since the bulkhead has many curved indentations and smaller flat areas, I had to abandon the block for the most part. Even my four-incher wouldn’t work very well in the constrained space. I’m not too worried about the smoothness of the finish on the bulkhead. I have concentrated on areas that are less obscured by parts either affixed to the bulkhead or by hoses and such. This section of the car body will just get a once over with sanding. I’ll do a spray of primer on the surface, followed by color.

The plan for spraying color is a little clearer to me now. I’m now planning on spraying color on the underside of the car and the front bulkhead first, perhaps with the interior and inside the trunk, too. My main interest is getting the body to a point where I can begin to reassemble sections like the independent rear suspension and the front end. It also seems prudent to hold off on spraying color on any exterior section until all the exterior is ready to accept color — including the bonnet.

That bonnet is now in a corner of the garage. When I need to clean excess primer off a brush, I smear it on the bonnet. That’s all I’m willing to do on the bonnet at this point. It can wait until I have a rolling body.

Detail body repair

The right door has required a lot of work, and I ran into a troublesome high spot that needed some hammer work and some additional body filler to remove a dip. The location is right in the vicinity of the “A” post, and it looks like one of those unfortunate dings that comes from a tree branch or something dropped.It seems a good occasion to go through the whole process of fixing the small ding at this stage in the priming and blocking process.

Detecting the dent — Why light is your friend
Although this dent was big enough to notice with the fingertips and from sand-through and left over “guide” spray paint, it’s good to see why light is your friend. The top photograph shows the “light line” that falls over the problem area. Of course, I didn’t need to see the line to see (or, rather, feel) the problem, but the line illustrates what happens when light hits a bump. You can set up a flourescent light to serve as a light source, but this often isn’t necessary. Most of the reflection comes from lights on my garage ceiling. For areas that are “below the curve” and therefore where I can’t use ceiling lights, I use a pair of halogen lights on a stand. I picked them up at the lumber yard for about $25 (USD) — a pair of 1000 watt halogens have come in handy.

Anyway, look for an interruption in the light line. You can usually get the feel for where the line ought to go with practice. If you are in doubt, use the vehicle’s symmetry to your advantage. Take a look at the light line on the corresponding section on the other side of the car.

It’s said that Sir William Lyons wanted to see an example of a pre-production car sprayed in black gloss so that he could look at the “light lines” of the design. In a sense, that’s what you do as you take in the light lines while block-sanding the primer. You look for the consistencies, or, rather, you look for the inconsistent in order to find the problems.

Hammer work and surface prep
Lots of times block-sanding an area will show you where the bumps and the dents are located. The dents or impressions keep the color of the guide coat that you lightly spray over the primed surface before blocking. They keep the color because the impression protects the paint from being sanded. High spots, the bumps, often appear because the primer below or even the base metal appears after block-sanding. I’ve heard to people using different colors of buildable primer simply to help identify high spots in this way. I suspect that using contrasting colored primers might make sense if there was great need to smooth a pretty rough area, but the project doesn’t seem to warrant that treatment.

Handling the high spots is easy. You tap them down. Do this gently and use lots of light taps on the high spot and in the vicinity. Stop frequently to see if you’ve tapped the spot enough. You should be able to tap a high spot down almost to the point where it is in line with the desired surface. If you overdo it, you’ll be able to handle the dent with filler. But remember that doing too much hammering has a tendency to stretch metal. And, at this point, you really shouldn’t be doing any but very minor adjustments. The majority of the body work should be behind you.

After the tapping is done, I use some 60 grit sandpaper to rough up the surface quite well, so that it accepts the body filler well.

“Easy Sand” body filler from Evercoat and block-sanding
The filler I’ve used for this final work is “Easy Sand” by Evercoat. Bill McKenna mentions it on his ’63 E-type FHC restoration website, and I found it at the local auto parts and body shop supply. The chain automotive stores, around here at least, don’t have it in stock. It is very good stuff. The filler comes in a tube-like bottle (see the picture), so dispensing it is easy and creates no mess at all. Like other fillers, Easy Sand is a two-part product, so it should be durable. The filler itself is very fine and goes on very smoothly — it’s more a cream than a putty. The manufacturers say it bonds well to metal, plastic, and primers.

The best thing about it for this kind of work is that it sands so nicely. When I’ve used other filler to bring up low spots in primer coats, I’ve always doubted whether the stuff would stick to primer, so I’ve ended up sanding right to the metal again. Also other fillers often sand badly when they are adjacent to buildable primer. The stuff usually is slightly harder than the primer, and so you have to be careful about outlining your filled area with a low spot in the primer. (Good blocking usually makes this less likely, though.) The Easy Sand product blocks very nicely.

I mix the filler on cardboard from soft drink containers or cereal boxes. I also use the cardboard to create a straightedge filler “knife.” These are probably not professional grade tools to use, but they have the advantage of being easy to clean up — you just throw them away. The downside of the cardboard filler knife is that it often doesn’t apply the filler smoothly. The third picture from the top shows the freshly applied filler, and it does have some troughs.

Block the area after the filler has cured. The area should be noticably better, though it might have a few imperfections. I noticed on this repair that I missed a small tap dent that I created while tapping down one of the high spots. It was not a particularly big dent, so I figured that the buildable primer would take care of it You can see the effect of the 60-grit sandpaper on the area. The two original high spots have merged to become one elongated spot, now flat from sanding. Flanking low spots have been filled with the filler. There isn’t very much filler left in the area, which is as it should be.

Repriming and blocking the repair
After the filler is blocked, it’s time to reprime the area. I use a paint brush to apply the primer, and that works quite well in small areas like this. After the primer is dry, block it again. This should bring the area to where you need it to be. I did this small repair after the second primer coat was blocked, and the problem was apparent. (This door has been a real job, and this little fix was nothing compared to the rest of the smoothing that was required. The big work was the result of many minor ripples all over the mid section of the door. That work was tedious mainly because getting the lines straight was complicated by the large surface area.) Any imperfections in the primed surface of the repair will get a at least one more going over before the surface is ready for color. I check the light line of the repaired area to see where it needs more attention. As you can see in the bottom picture, it’s in pretty decent shape, though it has some slight indentation yet. This will be taken care of in the next round of primer coat and blocking.

There is no doubt that these small repairs and the multi-staged priming and blocking is a time consuming process. But it’s also indispensible, unless you’re willing to settle for a less than acceptable finish.


October/November 2003 – Primer, block-sanding, coat two

Update: November 12 — It hardly seems worth an additional web page, so I didn’t add yet more pictures of the same old blocking. The focus was on the left door, and I was committed to conquering its waves. The blocking took all of the working weekend, amounting, I would imagine to a good ten-to-twelve hours. I noticed on Bill McKenna’s website that he spent 25 hours on his left door, so I figure that my work is about in line with his. There’s still another coat of primer to go on it, and I don’t know how many hours I spent working on it before this past weekend. As Bill says somewhere on his web site, it’s a wonder that people can actually make money doing a decent restoration. The hours required — and from skilled people, too — are formidable.

Speaking of Bill, I bought a replacement left frame from him. It was good to see his paint job in real life, at least a small portion of it. I’ve not done anything with the frame yet. I figure that can wait until I have the car body primed.

Second Coat of Primer

The car was turned into a pumpkin for Halloween. After the second coat of Tie-Coat Primer was good and dry, I put on another guide coat of flat spray paint. This time I found a half-can of hideous orange. It made the car look like a well ripened pumpkin — appropriate for the season. I took this picture after I happened to see where we were about a year ago. It turns out that we had just applied some POR-15 over the same area of the car after having removed paint. We were still pretty much in a tear-down and clean-up mode back in October-November 2002. It is good to see those old web pages, since it at least gives the impression of progress. Block-sanding tends to throttle that feeling, except of course when you tear into a bright orange marker coat!

It’s probably worth remembering that the point of doing multiple coats of high-build primer isn’t so much to coat the surface evenly with a thick coat. It’s really intended to allow you to even out low areas and obscure high areas, though of these two, I think that high areas are problematic. So in effect, you end up sanding most of the high-build primer off of the car. You leave a reasonable amount of primer on to assure a good bond of the topcoat to the surface. The temptation is to block the car a bit too little, leaving more than is needed to prepare the surface.

I get the feeling that this is really an art. And I also realize that good body work is worth the money people spend for it. It is labor-intensive and experience does count. (Too bad I have so very little experience!)

The second coat pretty clearly tells me that you really can’t spray the final primer coat and expect things to turn out all right. Despite my care while brushing the second primer coat, blocking it was complicated by the fact of the brush strokes. I found myself reblocking sections that had slight ripples from brush strokes, and I believe those areas would have been flat and ready for paint without the brushing. As a matter of fact, I think first coats are fine to brush, but probably not second coats.

For this priming of the car body, I will complete a second coat and second round of blocking the parts of the body that appear “from the curb” — the external sections of the body shell and the bonnet. The internal sections of these parts will get a single brushed primer coat and blocking. This includes the trunk (or boot), the firewall (or front bulkhead), the interior of the car, and the inside of the bonnet. I will probably spray color in the trunk, the interior, and the inside of the bonnet at that point. After all of this is done, I will spray a final coat of Tie-Coat Primer as smoothly as possible over sections of the car that are not already sprayed with color, followed by final blocking of those surfaces.

Of course, I could spray color on everything at once, though I am thinking that I’ll still have to spray color on the bonnet in at least two sessions, since I want to coat the inside of the bonnet thoroughly. This really means that the inside shell without the internal panels will need a separate spray session. The inside panels and the front valance (the lower “mouth” section) can also be painted separately. Once everything is together, another coat of color is in order.

Once again, the bonnet seems the complication.

I avoided doing the doors until I feel confident that I have a few more blocking tricks in my repertoire. I applied a bit more primer to a couple of low areas on the rear wings, and blocked them nicely into shape. Perhaps that tactic might help should I run into some irregularlities on the doors. I think that the doors are challenging because they don’t have the curves of the wings and the rest of the body. They are almost a pure tubular shape, and it seems difficult to get them just right. I also primed the trunk lid.

A couple of closing shots show where the blocking stands at the end of the weekend.

October 2003 – Paint-primer-with-a-brush hypothesis tested

Paint-primer-with-a-brush hypothesis tested

I mentioned at the close of the last entry that I was going to test out whether “high-build” primer could be painted on with a brush and still have it serve its purpose. Well, I didn’t use a typical sprayed “high-build” primer, though I used a “sandable/buildable primer.” The coating is “Tie-Coat Primer” that I needed to use to bond coatings to POR-15. POR-15 is very tough, and it has properties that make it tough to get regular primers to bond to it. Basically, you have to sand the surface rough in order to get primers or paints to stick to it. Or, you use Tie-Coat Primer.

I applied the Tie-Coat to the bonnet nose, which needed some smoothing in any case. I put on two coats, and after they had set I sprayed a thin coat of regular old flat black paint. The black paint was the “guide” coat that would mark where I had sanded and would highlight low areas on the surface. if the test worked the sanding after this initial primer would leave a perfectly smooth surface, leaving slightly rough and darker patches where low areas would be. High areas would become the color of the underlying POR-15, since the primer would be entirely removed with sanding. Only block sanding is allowed at this point. Taking some wet sandpaper in hand and trying it out with your fingertips just leaves grooves and usually frustrates the purpose of the marker paint coat, since your fingertips just follow the surface, however rough, and take off the paint.

The picture of the bonnet nose shows the light black marker paint over the buildable primer and the block-sanded surface. The bonnet, you might recall, has been a real challenge, and the marks show it. These marks are mostly well defined notches where body filler wasn’t adequately applied. Most low areas end up looking like shadows where wider, less detectable, depressions lurk.

I’m happy to report that the paint-primer-with-a-brush hypothesis tested out just fine. However, I do think there is a bit more waste of primer, and perhaps coats need to be applied a bit more thickly. This is because you have to sand through the brush marks, which appear quite clearly after the first swipes of the block over the surface. There also may be a bit of a tendency to remove too much primer in certain areas in order to remove brush marks. My suggestion is to remember to use reasonably long swipes of the block and avoid concentrating effort in any area. If you are using anything shorter than a 20-30 centimeter (about a foot) stroke with the block, you are probably going too hard at an area. If you use a small block to get at tighter areas or corners, be extra careful.

Because of the brush marks, I’m a little suspicious about applying final primer coats with a brush. It might be counter-productive, though I am going to see whether it’s possible by watching this project. I do think that brushing at least an initial coat makes good sense, and it probably can allow people to avoid a mess with sprayers.

A footnote: I was originally thinking that I would use Tie-Coat to prepare the surface to accept another high-build primer, but I learned from the POR-15 people that they don’t recommend mixing primers like that. They told me in response to an email question that Tie-Coat is a buildable primer and using another primer over it might have unexpected results. They responded quickly, too, I’m happy to report. I don’t know about the response, though, since it might have been designed to drum up more sales of Tie-Coat Primer. I’m not taking any chances, however. I’ll be using Tie-Coat as the one-and-only primer for this project.

Initial brush priming the body shell

After the bonnet experiment tested well, I went ahead and brush primed the body shell first with a thin coat of Tie-Coat Primer and then after it had set overnight a thicker coat — at least a coat that ended up with some drips here and there. After that coat set, I sprayed a dusting of the flat black paint as a marker coating. I made sure that the primer itself had set before I did any block-sanding. (Tie-Coat is supposed to accept topcoats after no less than 24 hours after application.) Since temperatures had been below 60 degrees Fahrenheit (about 15 Celsius), I gave the primer about 48 hours before I tried blocking.

I used 320 grit wet sanding on two different block sizes, a four-incher and a nine-incher. The smaller of the two worked very well on the rear upper quarter panels (the “humps” to each side of the trunk space over the rear wheels). The larger block worked merely acceptably on the larger flat areas on the sides and forward on the body shell. I say acceptably, since the right door gave me a fair amount of trouble. I had built up the rear lower section of the door so that it met the door frame, and I expected that there would be irregularlities that would come through in the marker paint. Oddly enough, the door blocked to a light blue, practically without a bit of marking paint appearing, even though irregularlities were quite easy to feel, and pretty easy to see when the piece was cleaned and shiny with water.

I should add that the “Carolina Blue” color of the primer was not my choice. That’s apparently the only color Tie-Coat comes in, or I would have chosen something else! This is the only time this car will appear light blue, at least as long as I own it.

But, back to the block issue. I didn’t want to use the longer home-made block, since it lacks the soft covering behind the sandpaper, and I didn’t want to gouge the surface with a slip. I do think that either I need to get better with the nine-inch block, or I need to find a much longer block to do the sides. I’ve noticed that the body folks at Classic Jaguar have a huge block with two handles on it to do the side panel and door work. The flat surface of that block must be about a meter long, since it easily straddles the length of the door and overlaps well over the ends of the door frame. A good long block would come in handy when you block up the body shell, the outer sills and the bonnet, I suppose.

Block sanding is not very interesting, though it does have some rules. First, keep the block parallel to the line of contact. In other words, if you are block-sanding a curved surface, the contact points of the surface should be a consistent line from the front to the back of the block. Second, move the block diagonally across the surface, first in one diagonal and then after you cover the surface, along the opposite diagonal. In effect, you make an “X” shape with the directions of your sanding over the surface. Third, thoroughly block the surface, but don’t dwell on any one place too long. With “high-build” primers, it’s pretty easy to oversand an area. And, fourth, use the block, not your hands. You can’t believe how many times you’ll be tempted to “touch” up an area with your fingertips. You can’t believe how many times you’ll screw it up. If you can’t resist the urge, use very, very, very light pressure with your fingertips, and don’t dwell on a specific area. I’ve found that even trying to rub down drips of the brushed primer with fingertips is counterproductive. The block is much better. You’ll need to keep the block quite wet, too. The primer soon turns into a gooey lubricant if you don’t rinse it off. I used warm water with just a few drops of dishwashing soap. The soap seemed to help keep the sandpaper clear, and yet there wasn’t so much in the water that soapy film became a problem. An old cake pan worked great as a container. Wipe the blocked surface with a wet cloth to get the sanded primer out of the way.

I got the entire external section of the upper body shell completely block-sanded in about seven hours, I would guess, after subtracting interruptions and breaks. Like I said, this is not very engaging work. It’s repetitive without a doubt.

I checked the surface by wiping it with some low-concentrate soapy water and then looking at the reflection of flood lights along the surface. The lines should be predictable, and you shouldn’t see small wavers (except where you’d be expecting them). The dark picture shows the floods reflecting against the right side of the car. There are some pit-like reflections that come from small soap bubbles. You can see a wavering of the reflection in the door, where irregularities widen the reflection. I usually get a good long reflection in view and then move up and down to see the reflected line travel across the surface. In the case of this side of the car, I should see a consistent line. I didn’t because of irregularities in the door panel. It still needs work. But the rear quarter panel is in pretty good shape.

I also used a little bit of Evercoat “Easy Sand” body filler to bring up a couple of areas on the left side — one flatness over the rear wheel well that I mentioned before and flatness where I repaired the “fillet” some time ago. Very little of the body filler was required. That Evercoat product, by the way, was good to use and seemed to set well. I now wish I had used the Evercoat body fillers from the beginning.

Second coat of primer

I decided to try brushing the second coat of primer. (I’m planning on three coats for external sections of the car.) Instead of applying a coat that would drip, I applied two fairly thin coats, and I’ve applied a third thin coat to areas I think need a little more coverage. I’ll let the primer dry well and apply a marker coat of paint sometime this week. Then it’s back to blocking again. I’m debating what to do about the nine-inch block. Do I try to use it again? Do I look for a longer block? Do I try to make a long block myself?