Tony Harrison 2 Posted January 31, 2017 Share Posted January 31, 2017 I've always had difficulty trying to fill gaps & holes, whether in house walls, plastic model kits, or (currently) trad-build aircraft kits. Typically, I spread filler generously (having prepared the surface well), allow to dry, rub down - but find the filler has shrunk, or I've rubbed it incorrectly or whatever, and there's a shallow hole that still needs filling. I can do this for days on end without getting anywhere. I am quite DIY competent, on houses and with kit building, but I have trouble with filler. Right now I'm filling the many gaps on a high-wing trainer style traditional kit, a US Carl Goldberg Mirage 550 kit from the '80s that should be rather nice eventually. I have some DeLuxe white filler, very light and easy to apply: I think it's way too soft, though. I have Ronseal light filler in a squeezy tube, a bit tougher but rather messy and it still shrinks into a gap, leaving a concavity. So what can people suggest as really the best filler(s) around, difficult to get wrong even for impatient heavy-handed types like me? Thanks, Tony Quote Link to comment Share on other sites More sharing options...
Don Fry Posted January 31, 2017 Share Posted January 31, 2017 Fillers are difficult. The temptation is to be economical with expensive materials. The temptation is to be thin on spreading because it dries quicker. They are both messages from the devil. Spread it on, leave to dry, sand off. And repeat. And repeat again. But three will do any job. But don't try shortcuts. They don't shrink, you didn't fill the hole. And old dry lightweight filler is reserected by taking a lump, and mixing with white glue, water, to a paste. And don't be tempted to grind with fine abrasive. A course abrasive used with no pressure, is a better tool than fine abrasive used with no care where the next stroke will fall, or with excess pressure. I have found over the years there is little difference between various makes, except that balsa is dusty, and they all benefit from either de dusting the job, or again mixing a bit of white glue to the filler. Quote Link to comment Share on other sites More sharing options...
Engine Doctor Posted January 31, 2017 Share Posted January 31, 2017 Try Wrapping your abrasive paper on a block of flat wood then you wont get the sinking in the middle as it will always keep the abrasive flat on the job . If you use just your fingers you will always get an poor finish . This applies to any finishing . water based filler will sink as they dry so make sure they are well dry before sanding . If using two part filler then job can usually be done with two application sanding between coats but water based fillers take longer to dry and may need thinner coats or they stay soft for longer so three or four applications depending on what your filling; again sanding off excess between coats , but always use a sanding block. Quote Link to comment Share on other sites More sharing options...
onetenor Posted January 31, 2017 Share Posted January 31, 2017 A thinned coat of white wood glue into the hole first then filler with a drop of white added applied when precoat is tacky if possible Don't use your fingers as backing for the abrasive paper use a block. Fingers leave "Tram Lines" in filler. If you can watch a body repair man rubbing down a car body and ask for some pointers When sanding convex surfaces use a rocking motion to avoid rubbing in flats. I think there are some facebook demos on sanding things down . P.S. precoat being tacky not imperative.If it dries it will still work But do not use much pressure as this may cause the surface to flex and that will cause the filler to crack off. Although adding the glue does help by adding some flexibility.Experimentation and practice will help Quote Link to comment Share on other sites More sharing options...
Stuart Z Posted January 31, 2017 Share Posted January 31, 2017 Posted by Engine Doctor on 31/01/2017 17:53:59: Try Wrapping your abrasive paper on a block of flat wood then you wont get the sinking in the middle as it will always keep the abrasive flat on the job . If you use just your fingers you will always get an poor finish . This applies to any finishing . water based filler will sink as they dry so make sure they are well dry before sanding . If using two part filler then job can usually be done with two application sanding between coats but water based fillers take longer to dry and may need thinner coats or they stay soft for longer so three or four applications depending on what your filling; again sanding off excess between coats , but always use a sanding block. Following on with ED's idea I glue sand paper to off cuts of 1/8th - 1/4" ply that are around 7-8" by 2" but of course you can pick a width to be wider than that. Different grade on each side and you can sand away very accurately. Just my two pence worth. Quote Link to comment Share on other sites More sharing options...
Tim Flyer Posted February 1, 2017 Share Posted February 1, 2017 I tend to use Isopon p28 car body filler on my models. It's polyester resin. Waterproof and strong. Excellent when using on glassed surfaces wood and metal. Hardens in about 20mins and can be sanded straight away. It sands easily too. Edited By Timothy Harris 1 on 01/02/2017 13:29:58 Edited By Timothy Harris 1 on 01/02/2017 13:33:25 Quote Link to comment Share on other sites More sharing options...
Engine Doctor Posted February 1, 2017 Share Posted February 1, 2017 Posted by Stuart Z on 31/01/2017 19:34:17: Following on with ED's idea I glue sand paper to off cuts of 1/8th - 1/4" ply that are around 7-8" by 2" but of course you can pick a width to be wider than that. Different grade on each side and you can sand away very accurately. Just my two pence worth. As Stuart says Gluing the abrasive paper to blocks is a good idea for sanding smaller items or modelling . I have made different shapes of block and glued abrasive to them for different profiles , especially concave shapes . Its also worth making them in various grades;Coarse for rapid removal of excess filler. Medium for shaping and then fine for final finish feathering the edges . Wrapping it around a block was just a general idea for sanding during general diy. For a two pack filler that set very quickly try Roneal Woodfill . Its lighter , sands easier than the isopon car filler and comes in either a white or biege that blends with balsa better. Quote Link to comment Share on other sites More sharing options...
Former Member Posted February 1, 2017 Share Posted February 1, 2017 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Tony Harrison 2 Posted February 3, 2017 Author Share Posted February 3, 2017 Thanks for the considerable advice here. I'm not a complete novice so (for example) I've known for many years about using a backing block for sanding (never use sandpaper with just fingers), and I've often glued strips of abrasive onto sticks or blocks: I find that glueing abrasive into the angles of right-angled aluminium profile, then fixing that into a vice, is a good way to sand leading edge profiles with lots of control. I also have a couple of Perma-Grit tools, heard about them on this forum and they're everything that people say - I'll get some more... Interesting tip about using white glue together with filler - I'll try it. And I might try Isopon too, used it many years ago on an old car. Thanks again, Tony Quote Link to comment Share on other sites More sharing options...
Stuart Z Posted February 3, 2017 Share Posted February 3, 2017 And another thought on fillers, I save the sanding dust from when I sand balsa - in a yoghurt pot and make filler with PVA and balsa dust. Saves getting the vacuum out every time you sand a piece and you are recycling your own plane! Quote Link to comment Share on other sites More sharing options...
McG 6969 Posted February 3, 2017 Share Posted February 3, 2017 +1, ... no, make it +2 for Stuart. Cheers Chris Quote Link to comment Share on other sites More sharing options...
OZ e flyer Posted February 3, 2017 Share Posted February 3, 2017 I find the stuff plaster board fixers use the best. It sands back easily, can be painted and doesn't hardly shrink so easy to sand. Quote Link to comment Share on other sites More sharing options...
Former Member Posted February 3, 2017 Share Posted February 3, 2017 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Stuart Z Posted February 4, 2017 Share Posted February 4, 2017 Posted by Percy Verance on 03/02/2017 21:48:25: Good thinking Stuart. But PVA doesn't usually sand too well as it tends to dry slightly rubbery. Aliphatic might be better in this respect as it dries harder. My brain fade, I do use aliphatic, can't remember the brand but yellow, not white pure PVA. Quote Link to comment Share on other sites More sharing options...
David Davis Posted February 4, 2017 Share Posted February 4, 2017 I have nearly finished putting this back into operational condition. It has not flown for the best part of twenty years and has had three engines in it. I have settled on an Enya 40SS but there are two large holes in the side of the forward fuselage which were drilled into it to allow access to needle valves etc, which are now redundant. I would like to fill them. Two questions: How do I de-grease the holes? Should I use water based filler or the automotive variety? Quote Link to comment Share on other sites More sharing options...
Rich too Posted June 11, 2017 Share Posted June 11, 2017 Make the holes bigger and cut out the grease area. I would use the P28 mentioned above. Edited By Rich2 on 11/06/2017 18:33:16 Edited By Rich2 on 11/06/2017 18:34:54 Quote Link to comment Share on other sites More sharing options...
Rich too Posted June 11, 2017 Share Posted June 11, 2017 I bought some Oracolour filler and it's liquid? Is it paint filler that needs spraying on? Doh! Quote Link to comment Share on other sites More sharing options...
Roger Price 1 Posted June 13, 2017 Share Posted June 13, 2017 I have used many of the fillers mentioned but find the best by far is 'Squadron' cellulose putty for all kinds of gaps. It is dry in a very short time and sands to a brilliant finish. Wouldn't be without it. Quote Link to comment Share on other sites More sharing options...
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