Saturday, 31 March 2007

Stripping Varnish

Stripping Varnish

This is a guide for removing varnish around and area where you have teak decks. Over time scrubbing and salt water can remove the timber away and you are left with proud Varnish. Water can sit here and often seep down through the caulking and under the teak, causing all kinds of problems you do not want to deal with.
You can use this method of varnish stripping for all manner of varnish, but I have recently done this kind and found a few obstacles to over come and will share them with you over this article. But keep in mind that there are many ways to do the same thing, so use this as a guide and if in any doubt please consult a professional varnisher.
Step 1:
Firstly, it would pay to put down some protection if you are near painted surfaces, or other varnish. Place two layers of the 14-day 3M 50mm blue tape on the surface under the varnish to be removed. This will be on here until all the first step of stripping and sanding is completed. Then with some cardboard, take a pattern of the radius on your rail. This will come in useful when re-creating the radius further on.
Use a heat gun on the varnish from the top of the radius to the under side. You won’t need to strip the top, as the belt sander will do that for you. Apply a steady heat to the varnish; until it appears to be lifting from the timber, you might hear a cracking sound. Carefully using a flat blade scrapper lift the heated varnish from the timber. The more you heat it the easier it should be. My only warning is to be careful around the painted areas, as heat can lift and bubble the paint also. You can use a stiff sharp blade scrapper for these areas.
Step 2:
It is time now to break out the belt sander. Place a 40 to 50-grit belt on, and lets get to it. What you plan to do here is to bring the raised or proud varnish area level again with the teak decking. Also removing any of the washed out areas of the decking in the process, so this doesn’t have to be repeated for the next few years. When you start with the belt sander, make sure the belt is fitted properly, and won’t slide around and damage you or your sander. You can also use a thin piece of plywood placed between the belt sander and the paint to avoid accidental damage to the paint or surface near the varnish. Wearing some earmuffs, dust mask, and safety goggles would be a good idea too. Start sanding the area, and work on a meter at a time, bringing the sanded varnish down to almost level with the decking. It will take some time to do this, and is a bit of a back breaker as well. Once you arrive with about 3mm of proud-sanded Varnish, it is time to think about keeping the whole area fair (nice and straight, level).
To do this move the sander in the same direction as the grain on the area you are sanding. It can be difficult to work out at first, but use your eye to look along the sanded rail and see if there are any humps of hollows. If so sand them down, or the surrounding area lower until you are happy. As you are fairing in the sanded rail, you should be close to being level with the decking. From here it is a matter of keeping the sander moving, and trying to sand the deck as well as the rail, whist keeping the area fair. It is a long process this part, and you will chew through the sanding belts too, but the end of belt sanding is in sight. Hang in there!
Step 3:
You might have noticed that the belt sander cannot reach all the areas. For here, it is time to use a sharp chisel and gently slice off the timber until it is level with the rest of the rail.
What is important above all else, is that the area you are working is going to look fair once the gloss varnish is re-applied. If you are working on an area where the decking stops and the rail continues, it’s a judgment call to how much you want to remove, whilst still keeping it fair and flat. Your eye never lies!
Don’t be worried about the caulked seams at this stage; they will be removed later.
Step 4:
At this stage almost all the varnish should be removed, and the belt sanded area is smooth and fair. It is time to re-create the radius using hand planes. Depending on the length of the rail you are working on is the size of the hand plane you will use. A No# 5 plane would work well for any areas around 3 meters and upward. There are larger planes available, but for this work its not really needed. For the shorter pieces of timber, use a No# 4, and a Block plane with a chisel to get the areas next to fitting’s or a painted edge. The cardboard template that was cut out in the beginning is the guide to the shape, the fairness is in making long even stokes down the rail, and working with the grain of the timber. You will know immediately if you are planning against the grain, as the timber looks rough and torn up. For any corner pieces use a block plane and work with the grain from the center outwards. Keep the blade on a shallow cut and sharp, no problem!
Step 5:
Let the sanding begin! Using 60-grit sandpaper, make up a short sanding board of about 200mm long, staple the sandpaper to it. This board is for sanding the long sections of rail. The motion used here will keep your radius fair and knock of any flat areas created by the hand planes. Starting on the top of the rail, roll the board over the edge of the radius, working in a length of a meter or so. Sand this method up and down the rail, always moving along. The radius will take shape and become fair fore ‘n’ aft, check the cardboard template every now and then to see if you have the correct shape, if not plane a bit more off until you are happy. It is the same procedure on the corner pieces and shorter section of rail, only using a cork block with the 60-grit, and the rolling sanding motion for constancy overall. For the areas by fittings, painted edges, and under the rail itself, hand sand until fair and all old varnish has been removed. Using a craft knife, and a narrow chisel, cut the caulking seams as close to the edge of the timber as you can. When the caulking is removed, lightly sand any that is left behind, and you are ready to go!
Step 6:
The time of the ‘Orbital sander’ has arrived. Place some 60-grit paper on to the sander, and sand all the top surface areas. This sand will take out the marks left by the ‘Belt sander’, which could be across the grain of the teak. It is important again to keep the orbital moving up and down the area of work. You will notice that the sander leaves tiny swirl marks behind, this is not a problem for the area of decking, you will not see it later on. Although on the varnished areas, it is important to follow the next procedures to insure that when you have finished varnishing that you cannot see any sanding marks.
Like before, board sand the radius with 80-grit this time, and the areas on the underside of the rail. Try to sand with the grain on all areas this time, it will make the final sand a lot easier. Next is to Orbital sand with 80-grit to the top of the teak, which is to varnished only. This will remove the sanding marks from the 60-grit sand earlier.

Step 7:
Just a little more sanding to go… Finally change to 120-grit sandpaper, and sand the entire top of the rail with the orbital sander. Then using the cork block and 120-grit, sand over where you have been with the orbital. This should remove any orbital marks, as you’ve come this far you want the finished product to look fantastic, with no swirls under the varnish. Hand sand the corner pieces and any other areas with the 120-grit; check over it all once more for any hard scratches left behind. If it’s all smooth, remove the blue tape, and wash down the entire area getting rid of all the dust and shaving’s. Now you are ready for the first coat of varnish.

Step 8:
Once the rail is dry, re-apply the blue tape to the edge. Try to mask within 3mm of the timber, you do not want too much varnish on the caulking. Make sure all the edges on the tape are pressed down firmly. You can use an airline to blow out any of the seams, just incase water is sitting in there; water doesn’t mix with varnish very well.
Use a nice Badger hair-brush for all the coats of varnish. It is time to mix the sealer coat, a 50/50 mix of varnish to thinners (reducer). Your preference comes into play here; you can use a single pack product to do this, or a 2-part system. The single pack product has a longer drying time, but leaves you with a rich, deep color the 2 part might not give. There are plenty of varnishes on the market these days, but I have chosen to go with 'Epifanes Gloss Extra UV' It doesn't dry as fast as the 2 part products, but its the color it gives the raw timber i like, and its surprisingly easy to apply. Mix your varnish to the correct ratios on the tin, adding 50% thinners to the mix. This will insure that it is nice and watery, and soaks into all the timber. This seals it up from water damage. Brush 3 hot coats (1 coat, then another onto it while it is slightly tacky); use a small brush to get down into the seams on the corner joints. Once you have applied the first coat, it will be difficult to see where you are when applying the next. Use the sunlight to show the wet edge of the new coat, and try to make each coat as smooth as the last. Leave it overnight to cure, or if it is cool, it could take an extra day to harden.

Step 9:
Remove the tape on the top part of the rail. Sand the top part of the rail with long even passes with the your cork block, keeping the area fair. This sand is only really to key up the varnish for the next coats. You won't sand the grain out this time around, and try to avoid sanding through to much, it changes the color of the timber. Block sanding the rail (with the grain) with 320-grit to get the seal coat unglossy and even. Sand under the rail, and the radius again by hand. Then you’re done. Wash down again, chamois dry. Re-tape the top edge of the rail to where the old tapeline was before.
Its time for more varnish! Mix the system you have chosen, and add about 10-30% thinner (reducer), enough to let the varnish flow out smoothly. These few hot coats are called ‘build coats’. They are to fill the grain, and give the varnish an appearance of depth. Wipe down and brush on the varnish, brushing back into the wet varnish will help keep it looking level. Apply 2 hot coats, like before. If you notice you are getting brush marks in the varnish, try to not brush back into the wet varnish to far, apply a bit more thinners or move along the rail faster. It will take sometime to get the hang of how varnish is applied. Just keep trying, you will find a solution to your method which will work for you. Leave to cure overnight.

Step 10:
Remove the top tape, and orbital with 320-grit. Sand to remove most of the varnish (or grain) this time, but try not to sand right back to the raw timber. Its hard not to and will most likely happen, but don’t be to worried, the next coat will cover it.
Hand sand the radius and edges with 320-grit. Wash down and chamois dry.
Ready for the next coat of varnish. The same as in Step 9, but only one coat this time. Hopefully it is getting easier now…

Step 11:
Hand sand lightly with 320-grit, to take all the dust marks off and any brush strokes, or runs. They happen also! Then rub over the entire rail with a purple ‘Scotch Brite’ pad. This gets down into any of the grain that is left, and dulls off any un-sanded glossy areas. Wash down and chamois dry.
Apply another coat of varnish the same as in Step 9.
Step 12:
You are now at a stage when the varnish should look pretty good. Most of the grain is filled, and its getting some depth to it. It is time to finish the caulking in the corners or joints in the rail. If the seam goes right through the timber, it will take 2 stages. Stage 1; is to mask up the seam to be caulked. Place some tape over the seam from the bottom to almost all the way to the top. Pump the caulking into the gap; using a narrow spout here is a good idea. It allows the product to get right down to the bottom of the seam, and the tape stops it from over flowing. Once that has cured overnight, pull the tape and re-mask the seams. Stage 2 is easy; squeeze some caulking into the seams, then run over with a spatula knife to smooth out. Pull the tape as soon as you can (have a rubbish bin near by, it can be very messy). You should be left with a nice seam, just make sure no one sits in it before the caulking has cured.
Step 13:
Now you are at the turning point. If you want to continue down the Single Pack path, carry on as you are. Or if you want to continue with the Two Part System, it would be best to get about 5 more coats of single part on the rail before you continue with the 2-part system. The single part varnish you put on now is going to fill the grain and make it look deep and full. Sand each coat lightly with 320-grit (as in Step 11). I have been able to put 1 coat on, let it cure, lightly sand, then apply another coat. You can get away with masking up for these 2 coats, but I wouldn’t do any more than 2 without re-masking. About 3-4 weeks later after the Single part varnish has fully cured and you feel that there is enough varnish to make it look deep and rich, lightly sand the rails with 320-grit, and apply 'Awl Bright' or 'Awl Grip Clear' (Awl Grip Clear is the gloss paint with out the pigment). I have parts of the yacht using this system which are over a year old, and still looking as good as new!
Getting 10 coats in total on the rail is about enough to keep it looking good. The time it stays nice depends on how much sunlight your yacht gets, and the product you use. You will have to keep on top of the varnish. Setting up a planned maintenance program of when you apply your next coat is advised. A rough guide to the varnishes is; 3-5 months for single pack, and 8-12 months for the 2-pack system. If you have any quires about varnish, ask your local professional for some advice. I’m sure they would be more than happy to help you out, there are no big secrets in the varnishing world…
Happy varnishing!

1 comment:

Funghi said...

Good stuff, mate! Perhaps you would consider going into more detail on the proper laying up of varnish, along with which types of varnish to use, etc. Or if perhaps you could direct me to a good online resource, that would be great. Thanks!