I still have not started working on the carriage (although I'm very near starting on its shafts) and am still working on a separate set of shafts. The amount of sanding required to sand out the brush marks has been gruelling. I have a special primer gun and all the equipment necessary to spray, and I can spray two coats per day of primer. The amount of time spent cleaning the gun will be more than offset in sanding time saved.
So this will probably be my last post on preparing a surface for painting by applying primer coats with a paint brush, so I wanted to give a quick overview of the steps leading up to sanding out the brush strokes in the primer.
Once again I have to back way up. Whenever you prepare to paint your carriage, you have to select products that you KNOW will be compatible with one another. For brush painting, I am using alkyd type enamels that are formulated for marine use. These paints seem to be sympathetic to the differences in materials found in a carriage, i.e. wood and iron or steel, solidly bound together.
Anything with lacquer thinner or acetone in it would destroy my finish, therefore, enamels and lacquers are not compatible. Rustoleum and Krylon are not compatible.
So far I have got three different brands of materials on this set of shafts: Pettit Clear Wood Sealer, Pettit Yacht White Undercoater, Schwartz* sandable primer, and some Rustoleum rattle-can metal primer. I knew beforehand that all these materials are compatible.
There is one coat of clear wood sealer on the wood, two coats of Yacht White Undercoater, which were sanded almost completely away, for filling grain and small imperfections, and four coats of Schwartz sandable primer. The primer was applied with the good quality badger hair brush.
There were many brush marks left in the primer. YOU CAN NOT PAINT THE BRUSH MARKS OUT WITH YOUR TOP COAT. Before you begin the process of applying your color coats, the underlying surface must be made absolutely smooth. So we need to get those brush marks out and here is how it's done.
You need:
220 Grit "wet" sandpaper
Some 180 grit wet sandpaper would be good too. 180 grit is coarser and could be used to take some of the initial brush strokes out, but should be used with care.
A bar of hand soap
Some assorted sanding blocks
A bucket of water...
Rub some of the soap into the bucket of water.
A large bucket of clean water
A large sponge
A clean chamois skin (NOT used on waxed cars!)
A nice day, some shade and a comfortable stool would be good, too!
As the last coat of primer was drying I applied a "guide" coat of a rattle can contrasting color (compatible Rustoleum). It is just a quick fog of spray over the primer.
The more traditional way to apply a guide coat is to thin some paint of contrasting color to about the consistency of ink and brush it onto the primer.
The purpose of the guide coat is to show you when you have sanded to a smooth surface and to warn you not to go any deeper. As you sand away with the wet sandpaper, the guide coat will remain in the depressions. When your surface is smooth, all the guide coat will have been sanded away.
You must be very careful not to sand all the way to wood! This is so easy to do, and is the reason for many coats of heavy bodied primer. Especially touchy places are around corners and sharp edges.
I have also found that if the first two coats of primer (or rough stuff) are a contrasting color to the following coats, it will tell you to STOP sanding before you get all the way to wood. On these shafts, the "rough stuff," the Yacht white undercoater, is white and the primer dark gray. The guide coat is also white.
So get comfortable and begin by adding a little hand soap to your small bucket of water. This lubricates the sand paper and makes things a little easier. Alternately, you can rub the sandpaper over the bar of soap.
Dip your sandpaper, wrapped around your sanding block of choice, into the soapy water and start sanding!
As you sand, fill up your big sponge with clean water from the big bucket and dribble it onto the area you are working on. This washes the sanding sludge away and makes sure you do not lose sight of the all important guide coat!
The chamois skin is used to help wipe away sludge and dry the surface.
On the left hand side, just a little of the guide coat has been sanded away, so that you can see how it lays in the depressions. When all the white speckles are sanded away, your surface will be smooth, and just about ready for enamel.
Sanding through to the wood is almost inevitable, but try your best not to! I have several small spots that went through to wood. I'll touch them up with (compatible) Rustoleum rattle can sanding primer, then CAREFULLY blend them back with some finer grit (probably 400) sandpaper. You can apply several coats of the Rustoleum primer within an hour.
I sanded on this set of draft sized shafts for probably four hours and got about 2/3 of the job done. This is when I made my decision to switch to priming with the paint gun.
I will have MANY more posts to come on painting!
___________________________________
*Schwartz Mfg. LLC
1261 W.200 S
Berne, IN 46711-9779
Schwartz Mfg. an Amish manufacturer of "Carriage Paint". Their black enamel is the shiniest, blackest paint I've ever seen and I REALLY like their sanding primer.
Hi Barb,
ReplyDeleteAs a builder of wood composite and wooden boats - and maintainer of same - two things I have found invaluable for paint prep have been steel wool and tack cloths. A third item I love is a shop vac. I clean out the canister of the shop vac REALLY well, as well as the hose and vacuum head. I then put the hose on the blowing OUT hole. I generally do not use any attachment on the open end for the boats - and NEVER use any attachment with a brush on it. On the smaller cart and carriage application, the flat corner (I call it the "nose nozzle") nozzle might be more appropriate.
I purchase my steel wool in the rolled bundle, as opposed to pads. I don't unroll the wool; the rolled bundle fits well in the hand and makes for a good sanding pad, while making it very difficult to get too much of a bite on the surface.
After wet sanding, I give a last going over with the steel wool. This is followed with the tack cloth. Any other dust/debris can be blown off with the shop vac. If I have time passing between last prep and first coat, I go over with a tack cloth immediately before painting.
The steel wool is great for the metal bits as well. It doesn't scratch like sand paper, it is stronger than rust and other types of grease and grit.
Finally, my personal favourite is brightwork - and wood boats have a TONNE of it! Brightwork here defined as polished wood. I only include this since so many carts and carriages have natural finished wood. Once the wood has been prepped, the first coat of varnish - and even the second - do well as a mix of 75% linseed oil to 25% varnish. This helps with moisture protection. Use steel wool between coats after completely dry. Next coat (or 2) would be 50/50 linseed oil to varnish, steel wooled between, then 25% linseed, 75% varnish, steel wooled. The following coats are 100% varnish and as many as desired, with steel wool "sand" between each. I lived on a 100 year old sailboat (no engine) with its original teak deck, doghouses, rails, boom, a (thrice replaced) wood mast, and original mizzen mast and boom. Treated as above was responsible for their longevity (although storms took the previous masts). That many coats might be overkill for a carriage. The takeaway is: the more coats initially, the less work later on - one can sand down a coat or two, add a coat or two and know the wood work is still protected.
Cheryl
Cheryl, what absolutely wonderful information! Thank you so much for contributing! I hope you'll stop by often, as there seems to be no central resource for people who want to restore their carriages and I am hoping that by sharing my experience, people will have an opportunity to learn. And I have NO problem if people can use the information here to restore boats! I have gleaned MUCH from wooden boat forums and old car forums. Thanks again!
ReplyDeleteBarb