I hate Polyfilla!

[Baldy881]

What am I missing with this stuff?

I have been building myself an aquarium cabinet from 18mm MDF and taken much care as this will be a predominant piece in the house (eventually).



(Note - there will be doors on to hide the ghastly yellow )

I always have the same issues with Polyfilla, it either sinks or raises after a period of time. Hands up, on a number of occasions i've taken short cuts by not touching in screw heads etc etc, so accept the less than perfect results, but on the above build i've done everything to the book.

I'm nearing the final coats of paint now but on close inspection this week (a number of weeks after the 1st coat of top paint) i've noticed a few of the screw areas on the cabinet have now raised, meaning more sanding and more painting

To summarise, I drilled, counter sunk, screwed, touched in with oil based paint (white gloss), Polyfilla filled, sanded, refilled, sanded, applied two coats of a primer, sanded and then did a first coat of final satinwood then left for a few weeks at which point all was perfect. Now it's not.

Why does Polyfilla do this?

[Nimby]

My guess would be that the screws have expanded and contracted more than the wood as the temperature varies, and while expanding they've pushed out the filler.

[Wozy68]

Baldy881 said:

Why does Polyfilla do this?

Using the wrong stuff matey. Use something like this, especially great on MDF.

http://www.autosessive.com/products/61727/superlit...

Like car bodies, timber contracts and expands, so its good on timber as well as MDF/Chipboard.

No doubt someone will come along in a minute and tell you NOT to use it, we've been using it for 20 plus years.
PS. Nicely finished cabinet by the way

Edited by Wozy68 on Thursday 21st August 12:33

[Renovation]

Everyone I know uses car body filler on timber.

Still have the same issue but I've always assumed it's the timber drying and shrinking rather than the filler expanding.

[nyt]

P38 FTW

[Baldy881]

Thanks chaps. I guess i'll sand it off one last time before applying the final coats of satinwood. At least the dark paint doesn't show up the minor imperfections so bad.

I know MDF can be a pain, even what paint to use on it (since MDF paint is like a chocolate teapot ). This was primed with watered down emulsion and top finish will be satinwood. I think it'll look good

Wozy68 said:

PS. Nicely finished cabinet by the way

Thank you, i'm very proud. From drawing the plans on a scrap of paper for B&Q to cut from, to putting countersink Blum soft close hinges on, have all been firsts with a very limited tool cabinet. Will end up costing me less than £80 for what is a replica of the EXTORTIONATELY priced item... http://shop.aquariumswest.com/ProductDetails.asp?P...

Thanks again for the advice

[bigdom]

Toupret filler, so much easier to use.

[Mr GrimNasty]

bigdom said:

Toupret filler, so much easier to use.

They make more than 1 type of filler you know - at least 1 is more or less the same as polyfilla.

Anyway, as suggested, just about any 2 part wood/car filler is fine.

Polyfilla seems to actually promote rust if it is in contact with unprotected nails/screws.

[scottri]

MDF saw dust and PVA glue mixed together seems to have worked ok for me before.

[hairyben]

Pollyfilla's completely the wrong product isn't it? Should you use a water-based product on mdf? I use pollyfilla regularly at work for plaster repair but use a wood filler at home for mdf work, never have a problem with either.

[Mr GrimNasty]

Like Toupret, Polyfilla is a brand name, they do wood fillers too. The assumption is the wrong type was used, but who knows!

[paulrockliffe]

Isn't the first port of call to find ways to not put screws through bits of wood that people will see?

I would have screwed through the top and bottom into the back and sides (and added some feet) or I would have used glue and biscuits before I would have started filling holes. There's also a myriad of hidden fixing systems, as normally employed by Ikea, that might have been suitable.

I asked a similar question a while ago and it was suggested I spend £300 on a pocket screw jig.

Looks good though, I suspect that no one will notice the imperfections other than you. So long as you don't invite any carpenters round and tell them you did it yourself of course.

[Fleegle]

I'd be using Toupret or 2 pack car filler, but I think the mistake you may have made is to use 'normal' MDF and not MR MDF. MR is much more stable

[Neil - YVM]

paulrockliffe said:

Isn't the first port of call to find ways to not put screws through bits of wood that people will see?

I would have screwed through the top and bottom into the back and sides (and added some feet) or I would have used glue and biscuits before I would have started filling holes. There's also a myriad of hidden fixing systems, as normally employed by Ikea, that might have been suitable.

I asked a similar question a while ago and it was suggested I spend £300 on a pocket screw jig.

Looks good though, I suspect that no one will notice the imperfections other than you. So long as you don't invite any carpenters round and tell them you did it yourself of course.

Ideally there would be no visible fixings.

As Wozy68 if it was to be painted then we would use car filler, P38.

£300 for a pocket screw jig, wow! a trend clamping one is about £60-70, and real simple ones are bout a fiver.

Also agree, the OP will probably be the only person that notices.