Spray filler?

[BanjomanParticipant @banjoman]

Experience, advice or recommendations?

[BanjomanParticipant @banjoman]

I wanted to ask if anyone here has any experience with spray-on fillers?

Of so, is there any advice you might be able to share and in particular, are there any brands or types that you could recommend?

I am looking for something to sort out a number of small, undeep dings and blemishes on a GRP hull surface, whcih it would be fairly hard work to fill if one went with a paste-form filler without at the same time creating a major spot sanding job.

It would have to be something that would not clash with acrylic paints.

Any tips, hints or suggestions would be most welcome!

/Mattias

[Dave MilbournParticipant @davemilbourn48782]

/Mattias

Not a lot of help to you maybe, but I use a high-build aerosol primer/filler sold by Halfords, a major UK retail and Internet supplier. It dries white and rubs down beautifully with 240 and 320 grit silicon carbide paper. It's totally compatible with Halfords acrylic (solvent-based) aerosol primers and gloss paints. I've no experience of using it with water-based acrylics like Tamiya, however. **LINK**
I've also used those two-pack car body high-build fillers which are intended to be sprayed on. If you mix them according to the instructions and apply with a brush then any brush strokes will be flattened out with the rub-down.They are, however, eye-wateringly expensive and usually only available in litre quantities (I didn't mind too much because Model Slipway were paying!)

Dave M

[Colin BishopModerator @colinbishop34627]

Something like Halfords primer filler should do the job. It is basically a thickened primer. You should be able to get similar automotive primer fillers where you are Mattias. I haven't used them very often but I know others do.

Colin

[BanjomanParticipant @banjoman]

Many thanks, Dave and Colin! I shall have a look around and see what I can find locally of that ilk; alas, rattle cans in general and solvent-based stuff in particular can be tricky to order over the 'net, as postal services tend to be averse to handling such stuff (although I recently managed to get some P38 sent to me from the UK by ordering it through the French version of Amazon).

/Mattias

[Peter FitnessParticipant @peterfitness34857]

I use a similar product available here in Australia, with excellent results. After rubbing down with appropriate grades of abrasive paper it provides a great surface for painting.

Peter..

[BanjomanParticipant @banjoman]

Thank you very much, Peter, and thanks again, one and all! I have just ordered a can of U-Pol High #5 through Amazon at just a few quid (including postage) above what Halfords ask.

And it goes without saying that, before applying any to the model, I will conduct the usual compatibility tests with the paints I intend to use on a test piece of some kind …

/Mattias

Edited By Banjoman on 09/08/2016 11:58:44

[BanjomanParticipant @banjoman]

I return to this thread in need of some further advice about rattle can-applied spray filler.

As mentioned in my Moonbeam-thread, I wanted to test the chemical compatibility between the U-Pol High#5 spray filler and the Vallejo RC Premium paints I intend to use for that build.

To this end I got some scrap plasticard, and proceeded to gouge and scratch its surface, so that I would also learn something about the filling capacities (or lack thereof) of the U-Pol.

In accordance with the instructions for use, I then applied two thin coats of U-Pol with ten minutes in between them.

I'll rteturn to the paint compatilibity results in the Moonbeam thread; what I would like to ask about here is a different matter altogether.

I noticed that in certain areas, the filler when dry had a number of pin-point but fairly deep holes in its surface (see below for image).

As I was not sure what might be the cause, I decided to conduct a second test.

One potential source might have been a reaction between the filler solvent and and the plasticard, so the second test was done on some scrap pieces of tin plate instead.

I also noticed when preparing the hardened filler to be painted that it could be dissolved with methylated spirits, which happened to be what I had used to degrease the piece of plasticard. I therefore wanted to test this parameter as well, and used in turn methylated spirits, kitchen degreaser and common washing-up liquid to degrease three pieces of tin plate, while leaving a fourth piece untreated.

These were then again given two light coats with ten minutes in between …

… and then rubbed down with 800 and 1500 grit wet paper.

There was no discernible difference between the four surfaces – all four were generally speaking very nice indeed, particularly after rubbing down, but all four also had some areas with the above-mentioned pin-prick size pitting of the surface.

I have very little experience of rattle cans – they and I have never really seen eye to eye, so I have long ago pretty much decided against them, whcih in turn of course means experience doesn't happen.

I know, however, that many a modeller here on the forum happily paints their models with spray paints, and I therefore wanted to know if the above problem is commonly known and has an appropriate solution?

One guess on my part is that might have been to close (I tried to observe the 20 to 30 cm suggested by the instructions, but its always tricky), and that the pitting may be from the propellant, but that is just a guess.

Does anyone have any good advice on how to avoid such pitting? It is rather awkward where it occurs, as it seems to go down more or less all the way to the underlying material, and thus will require some serious rubbing down if it were to occur on the model …

Mattias

Edited By Banjoman on 04/09/2016 15:42:50

[Paul FreshneyParticipant @paulfreshney24971]

This is i believe called Pinholing and the follow website explains why and how to resolve it.

https://www.autopaint18.com/html/pinholing.html

Paul Freshney

[BanjomanParticipant @banjoman]

Paul,

Many thanks for the link! Yes, pinholing seems to be what's occurring, and given the circumstamces, I'd be inclined to think either that the ten-minute interval between coats was too short, or that I have made several passes when applying each coat, and either way have managed to trap solvent underneath the top with ensuing pinholing.

If I decide to use the spray filler on the model (and I think I might) I shall thus take care to avoid both multiple passes of the same area, and wait a full hour inbetween coats.

If anyone else has any hints or tips, I'd still be more than delighted to get them!

Mattias

[Dave MilbournParticipant @davemilbourn48782]

Ten minutes is far too early. I adopt the Sniff Test with these rattle cans. Stick your nose right up against the painted surface after about an hour's drying time and have a good sniff. If there is even the remotest trace of solvent smell then leave it for another hour, then sniff again.

Overnight drying in a warm room is best. It's just plain daft to rush the painting of a model which has taken you dozens of hours to build.

Dave M

[BanjomanParticipant @banjoman]

Dave,

Indeed, on all counts!

I do plead in my (slight but still) defence, though, that I was only following instructions, as provided by U-Pol: **LINK**.

As for not hurrying a paint job on one's model, I completely agree; I will admit to having done a bit of a rush job on these test pieces, but would not dream of going at it in the same way when it comes to the real thing. Then again, one of the reasons why I decided to to a test piece in the first place was specifically bcause the product was new to me …

Anyway, the conclusion is yes, I will use the U-Pol filler, but will take utmost care with both the number of passes per coat and the time between coats!

Many thnaks to you all for your kind help and sound advice

Mattias

[harry smith 1Participant @harrysmith1]

Hi All

I am using MOTORSPRAY ONE STEP PRIMER PUTTY which sprays with shiny orange finish but sands to a dull orange, this makes the shiny low spots easily spotted.

I tested some blue spray putty from Super Cheap, but it was a thinner spray and to thin a mix.

I spray one day, sand and spray the next day.

Hope this helps!!!

Harry

[BanjomanParticipant @banjoman]

Harry,

Thank you very much indeed for your comment! The product you mention seems to be specific to Australia, but I'm inclined to think it likely to be similar to the U-Pol High#5 that I've gotten ,as that, too, is a car body spray filler.

We'll see how it turns out …

Mattias

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