What does it mean to seal foam?
The purpose of this is to stop the paint from being soaked into the foam. This gives the paint a smooth layer to sit on which gives it a smoother and shinier finish. Some people treat this layer as a way to fill imperfections such as small gaps and bumps but I strongly believe that all filling and sanding should be done prior to sealing the foam.
In this article, I aim to cover all of the methods I use to seal foam which includes:
The most common method is to use wood glue/PVA. These are more or less the same but I tend to find that wood glue is slightly thicker than PVA.
For PVA, I just go for the cheapest possible one (Homebase own brand). I find that this glue is thick but not so thick it requires any thinning.
For wood glue, I usually go for Gorilla glue because it reminds me of Harambe or the cheapest one that's labeled "Wood Glue" in my local hardware store. Depending on the thickness, you can apply it straight out the tub or you can thin it down. Some people suggest a 1:1 ratio with glue and water but since I'm lazy, I apply thicker and fewer layers. I use around 10:1 on glue/water. There is litearlly no need to measure it exactly. Just pour tiny bits of water in until the glue is thick but not too watery. It should drip off the brush like high sperm count semen.
When working with PVA/Wood glue, I would recommend being in an environment warmer than 10 degrees celcius and out of direct sunlight. To apply this, I get a cheap brush from poundland and smush the glue on the surface. You don't need much glue for each layer. Only use enough so it covers the surface. If it starts dripping, you've used too much. To get rid of brushmarks, dip your fingers in some water and give the surface a good fingering. Make sure your fingers stays well wet during this process. The reason for this is because if you're in a warmer environment, the glue tends to dry quite rapidly and dry hands will be counter productive in smoothing the glue. If you're working out in your garden on a summer day, I would recommend applying the glue in sections as oppose to all in one go to avoid it drying too quickly.
The drying process takes time and must not be rushed. Make sure at least 97% of the glue is dry before applying the next layer. You can tell the glue is dry when it turns clear as opposed to white. Dry time can be decreased in warmer enviroment. For example on a warm summer day, the dry time could be as little as 10-15 minutes to nearly 24 hours in the winter if you leave it in the garage. To speed things up, you can leave your armour in the airing cuboard but do make sure to put a piece of protective sheet down on the wood before you place your armour covered in glue on it! Make sure you go back to it every now and then to sort out any drips that may occur when the glue is setting. Do refrain from using a heatgun to dry your glue!! I usually apply no less than 3 and no more than 5 coats. I know some people who apply 7-10 layers!
The ones I use are Poly-Props SEAL and Plasti-dip. I prefer the SEAL as oppose to Plasti-drip and you can read the other article here. TL;DR Plasti-dip comes in a variety of colours but it is a bitch to use as it drips easily and SEAL has the texture of normal grey primer, doesn't drip as easily and is a tiny bit cheaper.
These sprays are significantly more expensive than the PVA method. A can would normally last you 2 and a half good coats on a full helmet or 2 coats on 2 pieces of small body parts (thighs, shins, arms)
To coat a full set of armour, you're looking at spending at least £100.
The pros of sprays:
Quick dry time (30 mins - 4 hours)
Evenly applied and no bursh marks
Flexible - whereas wood glue/pva will crack if you bend it
Eze Kote Resin
This is pretty new to me. It seals the foam extremly well and it is extremely thin. I could get away with 2 layers but I would recommend 3.
To apply this, you need a smooth brush, I usually use a make up brush (the one that looks like a bunny's tail on a stick) since they leave the least brush marks. Make sure your surface is dust/glue bits/hair free before apply it.
It's about as flexible as PVA is so the surface will crack if you flicked it. I got mine from here.
This is my least favourite method. It requires the most amount of care and takes the longest.
Latex may not always stick directly to the foam. A layer of adhesive should be applied on the foam before you start your latex work. Mixing contact glue with clean up fluids works well.
To latex, you'll have to be in a warm room. A foam brush is recommended to be used when applying latex as it does not leave brush marks. Dip the brush in the latex and brush onto the surface smoothly in one direction. Make sure you keep an eye on your piece and remove any drips as it occurs because you won't be able to remove drip marks once it's set! Basically it's a pain in the ass to work with. Pigments can be mixed in the latex to colour it. After applying a few layers (5-11 layers), you will have to seal it with some sort of magic spray but I just use clear lacquery from Halfords to remove the stickiness of it.
I get my latex from here.
[Section coming soon]
TL;DR The point of sealing foam is to stop paint from being soaked into the foam. If you're poor, use PVA/Wood glue. If you're not poor, feel free to experiment on other methods.